Understand the real-life science behind crime scene investigation Forensics For Dummies takes you inside the world of crime scene investigation to give you the low down on this exciting field. Written by a doctor and former Law & Order consultant, this guide will have you solving crimes along with your favorite TV shows in no time. From fingerprints and fibers to blood and ballistics, you'll walk through the processes that yield significant information from the smallest clues. You'll learn how Hollywood gets it wrong, and how real-world forensics experts work every day in fields as diverse as biology, psychology, anthropology, medicine, information technology, and more. If you're interested in a forensics career, you'll find out how to break in--and the education you'll need to do the type of forensics work that interests you the most. Written for the true forensics fan, this book doesn't shy away from the details; you'll learn what goes on at the morgue as you determine cause of death, and you'll climb into the mind of a killer as you learn how forensic psychologists narrow down the suspect list. Crime shows are entertaining, but the reality is that most forensics cases aren't wrapped up in an hour. This book shows you how it's really done, and the amazing technology and brilliant people that do it every day. * Learn who does what, when they do it, and how it's done * Discover the many fields involved in crime scene investigation * Understand what really happens inside a forensics lab * Examine famous forensics cases more intriguing than any TV show Forensic scientists work in a variety of environments and in many different capacities. If you think television makes it look interesting, just wait until you learn what it's really like! Forensics For Dummies takes you on a tour of the real-world science behind solving the case.
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Forensics For Dummies®, 2nd Edition
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Table of Contents
About This Book
Icons Used in This Book
Beyond the Book
Where to Go from Here
Part I: Cracking Open the Case
Chapter 1: Understanding the World of Forensic Science
Defining Forensics: The Science of Catching Criminals
Getting the Big Picture: Forensic Science in Action
Investigating the Crime Lab
Peeking Inside the Criminalist’s Toolbox
The Cornerstone of Forensic Science: Locard’s Exchange Principle
Chapter 2: Getting to Know the Forensics Team
Gathering the Evidence: The Criminalist at Work
From Analyzing Blood to Identifying Bugs: Forensic Science Specialists
Forensic Investigation’s Head Honcho: The Medical Examiner
Dealing with the Dead: The Coroner’s Technician
Testifying as an Expert
Chapter 3: Collecting and Protecting the Evidence
Assessing the Scene of the Crime
Classifying the Evidence
Locating the Evidence
Collecting and Preserving the Evidence
Locating a Missing Corpse
Chapter 4: Delving into the Criminal Mind
Defining the Role of the Forensic Psychiatric Professional
Assessing the Brain
Dealing with Deception
Assessing Competence and Sanity
Tracking Serial Offenders
Profiling the Perpetrator
Linking Criminals and Crime Scenes
Part II: Analyzing the Evidence
Chapter 5: Fingerprints: Your Personal Signature
Getting a Grip on Fingerprints
Making Matching Easier: Classifying Prints
Locating Those Sneaky Prints
Chapter 6: Painting A Gruesome Picture: Bloodstain Analysis
Understanding Blood’s Character
Analyzing Bloodstain Patterns
Putting It All Together: A Hypothetical Case
Chapter 7: Leaving Impressive Impressions: Shoes, Tires, and Tools
Stepping Out: Shoeprints as Evidence
Tracking Down Tires
Prying Clues from Tool Marks
Finding Facts in Fabrics
Chapter 8: Burning Down the House: Is It Arson?
Striking the Match: Looking into Fire-Starters
Determining Where and How the Fire Started
Heating Things Up: Accelerants
Investigating Homicidal Fires
Evaluating Explosive Situations
Part III: Examining the Body
Chapter 9: Determining the Cause and Manner of Death: Forensic Autopsies
Defining Death and Declaring It as Such
Shadowing the Forensic Pathologist
Performing an Autopsy
Filing the Official Autopsy Report
Chapter 10: Identifying Unknown Victims
Identifying the Body
Using DNA To Make the ID
Dem Bones, Dem Bones: Working with Skeletons
Chapter 11: Estimating the Time of Death
Defining Time of Death
Examining the Body to Estimate Time of Death
Gathering Other Clues
Chapter 12: Ouch! That Hurts: Traumatic Injuries and Deaths
Unleashing the Power of Guns and Gun Evidence
Slicing, Dicing, and Stabbing
Taking the Hit: Blunt-Force Trauma
A Shocking Situation: Electrocution
The R Word: Dealing with Rape
Chapter 13: Gasping for Air: Asphyxia
Gasping for Oxygen: Suffocation
Inhaling Deadly Air: Toxic Gases
Drowning: Water, Water Everywhere
Part IV: Utilizing the Crime Lab
Chapter 14: Analyzing Blood and Other Bodily Fluids: Serology
Blood: Life’s Most Precious Fluid
Identifying a Bloodstain’s Source
Testing for Paternity
Looking at Other Bodily Fluids
Chapter 15: Looking Deep Inside: DNA Analysis
Opening an Instruction Manual for Your Cells
Fingering Criminals Using DNA Fingerprints
Understanding the DNA Fingerprinting Process
Using DNA to Determine Lineage
Chapter 16: Testing for Drugs and Poisons: The Toxicology Lab
Examining the Testing Procedures
Looking at Common Drugs
Checking Out Familiar Poisons
Chapter 17: Picking Apart Trace Evidence
Defining Trace Evidence
Understanding Analytical Instruments
Splitting Hairs: Linking Crime to Coiffure
Fiddling with Fibers
Cracking the Mysteries of Glass
Puttering with Paints
Getting Down and Dirty: Soils and Plants
Chapter 18: Bang! Bang!: Analyzing Firearms Evidence
Figuring Out Firearms
Extracting Info from Ammo
Getting Groovy: Comparing Rifling Patterns
The Proof’s in the Powder: Gunshot Residues
Chapter 19: Questioning the Validity of Documents
Looking for Indentions
Examining Papers and Inks
Dissecting Typewriters and Photocopiers
Part V: The Part of Tens
Chapter 20: Ten Famous Forensic Cases
Using a Homemade Ladder: The Lindbergh Kidnapping
Sacco and Vanzetti and Sacco’s Gun
Ted Bundy’s Bite Marks
Stella Nickell’s Trail of Fingerprints
Finding Fibers on Jeffrey MacDonald
Georgi Markov and the Lethal Umbrella
The Hendricks Family’s Last Meal
Picturing John List
Being Anastasia Romanov
Faking Hitler’s Diaries
Chapter 21: Ten Ways Hollywood Gets It Wrong
The Quick Death
The Pretty Death
The Bleeding Corpse
The Exact Time of Death
The One-Punch Knockout
The Disappearing Black Eye
The Fast-Acting Poison
The Untraceable Poison
The Instant Athlete
The High-Tech Lab
Chapter 22: Ten Great Forensic Careers
Crime Scene Investigator
Forensic Pathology Technician
Forensic Document Examiner
Forensic DNA Analyst
About the Author
Connect with Dummies
End User License Agreement
Table of Contents
You probably purchased Forensics For Dummies, 2nd Edition, because you’re fascinated by the marriage of criminal justice and science. I wrote this book because I have a similar fascination. And you and I are not alone. Shows such as CSI: Crime Scene Investigation, CSI: Miami, and NCIS have dominated network television ratings for many years, attesting to the fact that millions of people agree that forensics is an interesting subject. Every criminal investigation you see on the news or read about in the newspaper, it seems, hinges on some bit of forensic evidence.
This book is designed to give you an understanding of the techniques and procedures used by forensic scientists. The next time you read or view a mystery story or hear a news report about a crime, you can turn to this book for the science underlying the story.
Forensics For Dummies, 2nd Edition, is an introduction to the field of forensic science, covering a broad range of forensic topics in a clear and concise fashion. I explain these often complex principles in plain English so that readers at all levels can gain a better understanding of forensic science. The book includes many examples of how these techniques are applied in real-life situations. In addition, I include case studies throughout the book to illustrate how forensic science has been used to solve famous cases.
If you know absolutely nothing about forensics, this book is an excellent starting point. If you’re familiar with many forensic topics, this book serves to refresh and expand your knowledge.
Note: The conventional language used by scientists is foreign to most people, so I hold scientific jargon to a minimum in this book. Still, as with other areas of science, the study of forensics can be dry and boring at times. To avoid painting such an arid landscape, I added practical examples of how each technique works, and I included many famous cases that relied on forensic science for their solutions. I also threw in a little humor to liven things up a bit. If my humor falls flat, remember, I’m a physician, not a stand-up comedian.
As I wrote this book, I made some assumptions about you and what your needs may be, including that
You have an interest in forensic science.
You’re a fan of the many forensic science shows that are aired on both network and cable television.
You avidly follow criminal cases reported on TV and in newspapers.
You’re considering a career in forensic science.
You love reading mysteries and want to better understand the science behind the stories.
You’re simply curious by nature.
Like other For Dummies books, this one has icons in the margins to guide you through the information and help you zero in on what you want to know. The following paragraphs describe the icons and what they mean.
This icon indicates that I’m giving you a look behind the scenes of a forensic practice or area of investigation. I use it to point out in-depth discussions of these concepts.
I use many real-life stories to illustrate the points in this book. This icon sets off these tales of crimes past.
Sometimes, to give you a clearer picture of how a forensic practice came about, I provide the historical background or a note about a related instance from long ago.
I flag certain pieces of information with this icon to let you know something is particularly worth keeping in mind.
Forensics deals with plenty of mind-blowing information about such things as the human body, evidence, and crime itself. For those of you who want just the juicy facts, look for this icon.
This icon signals that I’m going to delve a little deeper than usual into a scientific or medical explanation. I don’t mean to suggest the information is too difficult to understand — just a little more detailed.
This book is bursting with content, but you can go online and find even more. Check out the book’s Cheat Sheet at www.dummies.com/cheatsheet/forensics for tips on what to do if you witness a crime, tools of the trade in crime scene investigation, and more. And you can find some handy bonus articles related to forensics at www.dummies.com/extras/forensics.
Forensics is a broad and diverse field that involves many areas of science and criminal investigation. In this book, you can find out about many but not all of its concerns. You may use this book as a reference and as a springboard for further investigation. The next time you see a news report, read a mystery novel, or watch a movie involving a crime, you can turn to this book to obtain a better understanding of the science behind the story.
For Dummies can help you get started with lots of subjects. Visit www.dummies.com to learn more and do more with For Dummies.
In this part …
Discover how forensic science works.
Find out who makes up the forensics team and what they do.
Figure out how to properly collect and protect evidence at a crime scene.
Understand the inner workings of a criminal mind.
In This Chapter
Defining forensic science and checking out its origins
Understanding why the principle of evidence exchange is important
Unveiling how forensic science is organized
Revealing what services a crime lab offers
Turn on the TV any night of the week, and you’ll find crime scene investigators, or criminalists, tracking down criminals, crime lab technicians evaluating evidence, and even forensic pathologists conducting autopsies on shows detailing cases real or imagined. I don’t think this newfound interest in all things forensic stems from some macabre fascination with death or a guilty enchantment with the criminal world. If you ask me, people simply are curious by nature and have a strong appetite for scientific knowledge. Remember everyone’s fascination with the space program not too many years ago? The cool tools and magical feats of forensic science, such as making fingerprints appear from nowhere, identifying suspects by their shoeprints, sniffing out a forger by the unique signature of a laser printer, and finding even the most obscure poisons, are proving equally fascinating.
In this chapter, you get your feet wet with the basic definitions and organizational elements of the field of forensic science. Most of the topics that I touch on here are explored further in the chapters that follow.
If you lived in ancient Rome, you’d head to the forum when you wanted to discuss the news of the day. The town forum was a community meeting place for merchants, politicians, scholars, and citizens that doubled as a center for public justice. Steal your neighbor’s toga, and the case would be tried at the forum.
The term forensic stems from the Latin word forum and applies to anything that relates to law. Forensic science, or criminalistics, is the application of scientific disciplines to the law.
The same tools and principles that drive scientific research in universities and identify cures in hospitals are used by forensic scientists to reveal how a victim died and, ideally, who was responsible. In the same way modern hospital laboratories employ professionals to deal with pathology (the study of diseases of the human body), toxicology (the study of drugs and poisons), and serology (the study of blood), modern forensic laboratories employ experts in forensic pathology, forensic toxicology, and forensic serology, all of whom use the principles and testing procedures of their medical specialties to help resolve legal issues and answer questions like
When and how did the victim die?
Does the suspect’s blood match the blood found at the crime scene?
Was a suspect’s unusual behavior caused by drug use?
Not long ago identifying, capturing, and convicting criminals depended primarily upon eyewitnesses and confessions. The world was smaller, communities more closely knit, and the extent of travel basically only as far as you could walk. Whenever anyone witnessed a crime, he likely knew the perpetrator. Case closed.
Trains, planes, and automobiles changed all that. Criminals can now rapidly travel far and wide, and with this newfound mobility they are less and less likely to be recognized by an eyewitness. Besides, eyewitness evidence these days frequently is proven to be unreliable (see Chapter 3).
For law enforcement to keep pace with these changes, other techniques for identifying criminals had to be developed. Science came to the rescue with methods that depend less on eyewitnesses to identify perpetrators or at least link them to their victims or crime scenes. Fingerprinting (Chapter 5), firearms identification and gunshot residue analysis (Chapter 18), hair and fiber studies (Chapter 17), blood typing (Chapter 14), DNA analysis (Chapter 15), and many other scientific techniques now help solve crimes that would’ve remained unsolved in the past.
The marriage of science and law hasn’t been without its setbacks. Many scientific breakthroughs are viewed with suspicion, if not downright hostility, until they become widely accepted. And before a science can ever enter the courtroom, it must be widely accepted. It should come as no surprise that before forensic science could develop, science in general had to reach a certain level of maturity.
The development of modern forensic science parallels general advancements in science, particularly the physical and biological sciences. Take a look at how a few milestones in science pushed forensic science several steps forward:
The invention of the microscope enabled criminalists to analyze even the smallest bits of evidence and to see details in evidence that never before were imagined.
The development of photography gave criminalists a crystal-clear representation of the crime scene without relying on memory or the slow process (and far less detailed results) of making drawings.
The understanding of the physics of ballistic trajectories gave criminalists a much clearer idea of where a bullet may have come from, which, in turn, made crime-scene reconstruction more accurate.
The discovery of blood typing and DNA analysis made matching suspect to crime scene far more exact.
The expansion of our knowledge in basic chemistry allowed scientists to identify chemicals and poisons, particularly arsenic, and led to the development of forensic toxicology.
You witness a burglar sneaking away from a store late at night. You call the police, and when they arrive, you identify the thief as someone you know. That person is arrested. However, fingerprints from the store’s broken window, cracked safe, and tools used to open the safe don’t match those of the person you’ve identified. Instead, they match the fingerprints of a known safecracker. What do you think police, prosecutors, and more importantly, the jury are going to believe? After all, it was dark and raining, you were 100 feet away, you caught only a glimpse of the thief, and you’d just left a bar where you’d had a couple of drinks with friends. The fingerprints, on the other hand, match those of a known thief in each and every detail, meaning they came from him and only him. Which bit of evidence, the fingerprints or your eyewitness account, is more reliable?
This scenario represents what forensic science does, or at least attempts to do. Each and every forensic technique that you discover in this book is designed to either identify perpetrators or connect them to the crime.
Properly identifying, collecting, documenting, and storing evidence are at the heart of the forensic services offered by virtually all law enforcement agencies, from village cops to major metropolitan police departments. They need the basic services in the list that follows to be able to investigate and solve crimes and to convict the criminals who commit them:
Evidence collection unit:
rime-scene investigation unit
collects and preserves evidence from the crime scene and transports it to the lab. Regardless of whether they’re individual police officers or highly trained professionals, members of this unit expose and lift latent fingerprints (
), collect hair and fibers (
), and gather any other articles of evidence at the scene.
takes pictures of the crime scene, all evidence, and the body (whenever one is present). These photos are crucial, serving as blueprints for crime-scene reconstruction and an excellent format for presenting evidence in the courtroom. Turn to
to find out more about photographing a crime scene.
A secure place for storing and preserving the evidence is essential. Evidence usually is stored in a locked room with restricted access that is housed at your local police station or sheriff’s department. Evidentiary materials are kept in storage for years or even decades, and the chain of custody (see
) must remain unbroken throughout that time, or the evidence can be compromised, losing its value.
Tracking down trace evidence, checking the characteristics of bullets fired from a gun, examining the penmanship of a signature on an important document, and evaluating the swirling ridges of fingerprints under a microscope all are part of the physical side of forensic science.
Any small item of evidence, such as hair, fiber, paint, glass, or soil, for example, that places the suspect at the scene of the crime or in direct contact with the victim is considered
Matching glass fragments found on the victim of a hit-and-run motor-vehicle accident to glass from the broken headlamp of the suspect’s car is a prime example. Find out more in
deals with the identification of weapons and the projectiles they fire, including ammunition, fired bullets, shell casings, and shotgun shells. Firearms experts use a microscope and various types of chemical analysis to identify the type of weapon used to commit a crime and match any bullets fired from that weapon or shell casings to a suspect weapon. I cover firearms examination in
Whenever an important written document’s age or authenticity is in doubt, a
uses handwriting analysis to match handwriting samples to questioned documents or signatures. Document examination also may include analyzing the physical and chemical properties of papers and inks or exposing
(the impressions made on the page beneath one that was written on). Typewritten or photocopied documents that may have been altered also fall under the document examiner’s area of expertise. Check out
for the details.
match prints to the fingers, palms, or soles of the people who left them at the crime scene. A print found at a crime scene can be compared with another taken from a database or from a suspect, victim, or bystander.
tells you all about fingerprint examination.
Forensic science deals not only with physical evidence but also with biological evidence, which may take the form of a corpse, skeletal remains, drugs and poisons, teeth, bite marks, insects, and plant materials, to name a few. It also includes analysis of the criminal mind. Biological evidence is often what makes or breaks a case.
For example, an autopsy (postmortem examination of the body, which is discussed in Chapter 9) may reveal the nature and cause of any injuries, the presence of any poisons, and ultimately why and how the victim died. These findings alone may lead to the perpetrator. Blood and DNA analysis can positively identify suspects and link them to crimes. DNA and dental pattern records can be used to identify an unidentified corpse, and plant and insect evidence can reveal the time of death and link a suspect to the crime scene. Find out more about these sciences and the people who specialize in them in Chapter 2.
Although they use much of the same equipment and follow similar research procedures, forensics (crime) labs are quite different from medical (clinical) labs. The latter deal with the living by carrying out testing aimed at diagnosing and treating the sick. On the other hand, forensics labs are geared toward testing evidence with the hope of establishing links between a suspect and a crime.
The United States’s first forensic laboratory was established in 1923 by August Volmer in the Los Angeles Police Department. Shortly thereafter, the first private forensic lab was created in Chicago in 1929 as a result of the investigation of Chicago’s infamous St. Valentine’s Day Massacre (see the nearby sidebar). This case involved the expertise of Calvin Goddard, then America’s leading firearms identification expert, who was able to link the killings to Al “Scarface” Capone. Two businessmen who served on the coroner’s inquest jury were so impressed with Goddard and his scientific use of firearms identification that they funded the development of a crime lab at Northwestern University. The lab brought together the disciplines of firearms examination, blood analysis, fingerprinting, and trace evidence analysis and served as a prototype for other labs.
In 1932, Goddard helped the Federal Bureau of Investigation (FBI) establish a national forensics laboratory that offered virtually every forensic service known to law enforcement across the United States. It, too, served as a model for future state and local labs. Now many states have networks of regional and local labs that support law enforcement at all levels.
During the height of Prohibition, gang warfare raged over control of the illegal alcohol trade that sprang up in many U.S. cities. None was bloodier than the war between Chicago rivals Al “Scarface” Capone and George “Bugs” Moran.
On the night of February 14, 1929, seven of Moran’s men were waiting for a shipment of hijacked liquor in a warehouse on Chicago’s Clark Street. Unbeknownst to them, the shipment was a setup orchestrated by Capone in an attempt to kill his chief rival, Bugs Moran. Moran was supposed to be at the warehouse, but he arrived late. When he got there, he saw a police car pull up and five officers enter the warehouse. Moran retreated and heard machine gun fire, then saw the five cops come out and drive away.
The real police arrived and found that each of the seven men had been shot numerous times. They recovered 70 shell casings. Bullets later were recovered from the victims. Cardiologist Dr. Calvin Goddard, who became famous during the Sacco and Vanzetti case (see Chapter 20), was called in because of his expertise in firearms identification. He determined that the shell casings were from Thompson submachine guns. Using the newly developed comparison microscope, he tested casings from Thompsons belonging to police and determined that none of them were the murder weapons. Goddard’s findings meant that the killers had impersonated police officers. Suspicion fell on Capone. Police raided the home of one of Capone’s hit men, finding two Thompsons that later were identified as two of the murder weapons.
Scientific services offered by modern crime labs and medical examiners’ offices are varied and complex. The number of services supplied by a particular laboratory depends on its size and budget. State and regional labs may provide a wide array of services, whereas local labs may provide only basic testing. These smaller labs typically outsource more sophisticated testing to larger regional labs. In addition, the FBI’s National Crime Lab offers services to law enforcement throughout the country. Not only does the FBI lab perform virtually every type of test, it also possesses or has access to databases on everything from fingerprints and tire-track impressions to postage stamps.
Larger labs often feature separate departments for each discipline, while smaller labs tend to combine services, perhaps even relying on a single technician to do all the work. Obviously, in this circumstance, a great deal of the work must be sent to larger regional labs.
Common procedures conducted in a crime lab include
Fingerprint analysis (
Tool-mark and impression analysis (
Blood analysis (
DNA analysis (
Toxicological testing (
Trace evidence evaluation (
Firearms examination (
The first forensic scientist came not from the world of science but from the world of fiction. Sir Arthur Conan Doyle’s character Sherlock Holmes frequently used the sciences of fingerprinting, document examination, and blood analysis to solve the crimes he investigated. In fact, in the first Sherlock Holmes’ novel, A Study in Scarlet, Holmes developed a chemical that determined whether a stain was blood.
Similarly, Mark Twain employed fingerprint evaluation in two of his works (Life on the Mississippi and Pudd’nhead Wilson) nearly a decade before they became recognized investigational tools.
The first real-life forensic scientist was Hans Gross. In 1893, he published the first treatise on the use of scientific knowledge and procedures in criminal investigations. Others soon followed.
In 1901, Karl Landsteiner discovered that human blood could be grouped and devised the ABO blood groups that still are in use today. In 1915, Leone Lattes developed a simple method for determining the ABO group of a dried bloodstain and immediately began using it in criminal investigations. Today, ABO typing, though not able to absolutely identify a particular person, is used to exonerate some suspects, to refute paternity, and to reconstruct crime scenes.
Early in the 20th century, Calvin Goddard perfected a system for comparing bullets under a comparison microscope to determine whether they came from the same weapon. And, Albert Osborn laid down the principles of document examination in his book, Questioned Documents, which still is used today.
Crime-scene investigators are charged with finding, collecting, protecting, and transporting all types of evidence to the crime lab. Although each person or team may have different ways of doing things, typical equipment and supplies they take to the scene include the following:
Crime-scene tape to demarcate and secure the scene
Camera and/or video recorder to document the scene and the evidence
Sketchpad and pens for scene sketches
Disposable protective clothing, masks, and gloves
Flashlight-alternative light sources such as laser, ultraviolet, and infrared lighting for exposing certain types of evidence
Magnifying glass, tweezers, and cotton swabs for collecting hair, fiber, and fluid evidence
Paper and plastic evidence bags and glass tubes to collect and transport evidence
Fingerprint supplies, which include ink, print cards, lifting tape, and various dusting powders and exposing reagents such as luminol
Casting kit for making casts of tires, footwear, and tool-mark impressions
Serology kit for collecting blood and other bodily fluids
Entomology kit for collecting and preserving insect evidence
Hazmat kit for handling hazardous materials
Every contact you make with another person, place, or object results in an exchange of physical materials. If you own a pet, this material exchange is well known to you. Look at your clothes and you’re likely to see cat or dog hair clinging to the fabric — a pain in the behind if you want to keep your clothes looking sharp, but an incredible boon for forensic science. You may also find that you transfer these hairs to your car, your office, and any other place you frequent.
Known as the Locard Exchange Principle, after Dr. Edmond Locard, the French police officer who first noticed it, the exchange of materials is the basis of modern forensic investigation. Using this principle, forensic scientists can determine where a suspect has been by analyzing trace evidence (any small piece of evidence), such as fibers on clothing, hair in a car, or gunk on the soles of shoes.
As an example, say that you have two children and a cat. You run out to take care of some errands that include stopping at a furniture store, the laundry, and the house of a friend who has one child and a dog. From a forensic science standpoint, this sequence of events can provide a gold mine of information.
You leave behind a little bit of yourself at each stop, including
Hair from yourself, your children, and your cat
Fibers from your clothing and the carpets and furniture in your home and car
Fingerprints and shoeprints
Dirt and plant matter from your shoes
Biological materials, if you accidentally cut yourself and leave a drop of blood on the floor or sneeze into a tissue and then drop it in a trash can
But that’s not all. You also pick up similar materials everywhere you go:
Fibers from each sofa or chair you sat on at the furniture store ride away on your clothes, as do hair and fibers left behind by customers who sat there before you.
Fibers of all types flow through the air and ventilation system and settle on each customer at the laundry.
Hair from your friend, her child, and her dog latch on to you as do fibers from your friend’s carpet and furniture.
Fibers, hairs, dirt, dust, plant material, and gravel are collected by your shoes and pants everywhere you set foot.
In short, by merely running errands, you become a walking trace evidence factory.
An examination of your clothes and shoes after the preceding expedition essentially provides a travelogue of your errands. If someone robbed your friend’s house that evening while your friend was away, criminalists would find your fingerprints, your hair (as well as that of your children and your cat), and fibers from the carpets in your house and car. They could place you at the scene of the crime.
Of course, you’d have an alibi (I hope) and a legitimate reason why your trace evidence was found at the scene. The thief would not be able to offer a legitimate reason for his trace evidence being at the scene, which means the presence of his prints, hair, and carpet fibers would need an explanation.
Placing a suspect at the scene of a crime is one of the basic functions of forensic science. The analysis of fingerprints, blood, DNA, fibers, dirt, plant materials, paint, glass, shoe and tire impressions, and indeed every test done by the crime lab, is performed to create an association between the perpetrator and the crime.
In many cases, the mere fact that a suspect can be placed at the scene is an indication of guilt. A fingerprint on the faceplate of a cracked bank vault, semen obtained from a rape victim, or paint from the fender of a car involved in a hit-and-run accident connects suspects to crime scenes where they have no innocent reason for being.
In This Chapter
Checking out the duties of criminalists
Looking at forensic science specialties
Understanding the medical examiner’s duties
Getting to know the forensic investigator
Offering expert testimony in court
TV forensics teams have it good: There’s a specialist for every possible field of study and a fancy piece of equipment for analyzing whatever evidence comes in. Unfortunately, that’s not the case even in larger, more sophisticated jurisdictions, much less in smaller ones where law enforcement officers or a single or very small number of criminalists perform all the required duties.
More often than not, this is due to funding shortfalls. The truth is that most crime labs are severely underfunded. This fact led author Jan Burke to create the Crime Lab Project (https://crimelabproject.wordpress.com), a site that helps raise public awareness of this national problem.
Police typically are the first officials to arrive at any crime scene. After they determine the nature and exact location of the criminal act and secure the scene, they call in various forensic specialists to document and gather evidence, and then transport it to the crime lab for further testing. Who shows up to handle these duties depends upon the resources and structure of the jurisdiction.
Larger crime labs may have a special crime-scene investigation unit (CSIU) that consists of individuals trained in evidence recognition, collection, and preservation. They are also skilled in performing many of the field tests and screening tests that must be done at a crime scene. Although their exact titles and duties vary from jurisdiction to jurisdiction, these specialists can be divided into two groups. I use the terms criminalists or forensic investigators for those who deal with the physical evidence and coroner’s technicians to refer to those who deal with the body in cases of death.
Criminalist is a relatively new term and one that’s not easy to define. It covers a wide range of abilities, responsibilities, and training. Some, such as serologists and chemists, are scientists, while others, such as fingerprint and firearms examiners, are likely to be ex-police officers who have no true scientific training. Still others are technicians with on-the-job training.
No matter what their specialty or education, the bottom line is that criminalists work with evidence. That can mean a lot of things, from looking for poisons in blood samples to authenticating written documents, but all of it falls under the banner of criminalist.
In spite of what you see on TV and in the movies, criminalists aren’t cops (although, in some cases, they are former police officers). They don’t carry guns, interrogate suspects or witnesses, or make arrests. They don’t treat the injured or deal with a dead body. They collect and analyze evidence. That’s it.
Common job titles for criminalists include the following:
These are the CSI guys and gals who visit the crime scene to locate, collect, protect, and transport any and all evidence to the crime lab. They document the scene by sketching and photographing it, unless there is a sketch artist or photographer on the scene to take over this duty at their direction.
Latent print examiner:
These specialists examine fingerprints as well as palm and footprints and compare them with prints obtained from suspects, other crime scenes, or print databases.
gives you the skinny on fingerprints.
The duties of this individual include examining and identifying firearms, comparing bullets and shell casings, and searching for and identifying gunshot residue.
gives you the details.
Like fingers, tools leave behind distinct markings that may connect them to a crime scene. Tool-mark examiners compare these marks to suspect tools. I cover this practice in
These experts examine various documents to determine their authenticity and authorship and to look for any alterations in a document’s original content. They may also be asked to identify whether a particular typewriter or copier produced a certain document. Check out
Trace evidence examiner:
These specialists analyze and compare hair, fibers, glass, soils, and paints to determine their type and origin.
tells you more about analyzing trace evidence.
I’m sure you’re familiar with the TV series CSI: Crime Scene Investigation and its many spin-off shows. How could you not be? Though they more often than not get the science right, they create an unrealistic picture of what a crime lab looks like, how well equipped it is, and what CSI and lab techs actually do. But, like other more scientifically based shows like Forensic Files, for example, these shows have raised public awareness of forensic science and introduced viewers to the world of forensic investigation.
One unintended consequence of these shows and the raised public awareness of forensic science procedures is the CSI Effect. Though controversial as to whether it actually exists, many experts believe it does, while others feel it doesn’t. Regardless, it makes sense that saturating the public with all this forensic science would naturally change its view on criminal investigation and prosecution. Those who support the existence of this effect point to three major areas: the public, and thus jurors; judges, prosecutors, and defense attorneys; and criminals.
Whenever a high-profile case pops up on the news, the public seems to immediately jump to whether there is DNA evidence or not. If there is, the suspect must be guilty, and if not, he must be innocent. The facts are that DNA analysis is only relevant in a very small percentage of cases, perhaps as low as 5 percent. Most crimes are solved by good police work, not the crime lab. This attitude naturally enters the courtroom where jurors are asking the same question: Why is there no DNA? Did the police do something wrong by not collecting it? Is there no DNA because the defendant is innocent? You can see how this complicates the job of prosecutors and defense attorneys. If jurors expect forensic evidence to be presented to support their cases, these attorneys need to explain any absence of such evidence.
And what about criminals? They watch these shows. They learn what law enforcement and crime labs can do. They wear gloves when breaking into a home to avoid leaving fingerprints, they wear condoms in rapes to avoid leaving behind DNA evidence, and they take other steps to avoid detection. Fortunately, a little knowledge is a dangerous thing, and as you see in the remainder of this book, criminals may avoid leaving behind one type of evidence while ignoring other, equally damning, evidence. And that’s a good thing.
If you need to find out how a victim died or identify a piece of a plant found at a crime scene, you call on a forensic scientist trained in pathology or botany, respectively. Professionals who work in the various forensic biological sciences are among the most highly trained and skilled members of the forensics team. They include the following:
Pathologist: A forensic pathologist is a licensed physician with specialty training in pathology, which deals with the nature of disease and the structural and functional changes it causes in the human body. In addition, the forensic pathologist takes subspecialty training in forensic pathology, the application of pathological science to the law.
The forensic pathologist is in charge of the body and all the evidence that is gleaned from its examination. He uses the autopsy, police report, medical records if indicated, suspect and witness interviews, the results of crime lab evidence evaluations, and much more in the pursuit of answers. The forensic pathologist also examines living victims to determine the causes and ages of injuries, particularly in cases of assault, rape, or abuse. Part III of this book focuses on forensic pathology.
studies human skeletal remains to determine the age, sex, and race of the deceased, identify any illnesses or injuries that the victim may have suffered, and to estimate the time of death. The forensic anthropologist examines not only the recovered bones, but also the location and circumstances in which they were found. Toxicological, chemical, and DNA analyses also are used by the forensic anthropologist. Other responsibilities may include identifying victims of mass disasters and those interred in mass graves. You can find out more about forensic anthropology in
(or forensic dentist) helps identify unknown corpses by matching dental patterns with previous X-rays, dental casts, or photographs. Because dental enamel is the hardest substance in the human body, forensic dental services can help with identifying homicide victims, victims of mass disasters, and skeletal remains. Forensic odontologists are called upon to match a suspect’s teeth with bite marks on the victim or on food products such as cheese or apples.
tells you more about forensic odontology.
is the study of insects. The
uses knowledge of the life cycles of flies and various other insects that feed on corpses to determine the approximate time of death. Likewise, the forensic entomologist uses knowledge of insect habitats to determine whether a body has been moved from one location to another. Find out more in
may be asked to address someone’s sanity or competence to stand trial, sign documents, or give informed medical consent. In suicide cases, forensic psychiatrists may be asked to conduct psychological autopsies to determine possible motivations of the deceased. A forensic psychiatrist may also be asked to provide a psychological profile of an unknown perpetrator. Check out
for the lowdown on forensic psychiatry.
lab deals with blood and other bodily fluids such as saliva and semen, identifying the presence or absence of antigens and antibodies in those fluids. Blood typing, paternity testing, and in some labs even DNA profiling are conducted by the
is the study of drugs and poisons. The
determines whether drugs or poisons are present in the living and the deceased, often to assess how those substances contributed to aberrant behavior or death. The forensic toxicologist also determines whether drivers were intoxicated or workers violated company drug-use policies. Check out
for the full scoop on toxicology.
Examining plant residues, one of the tasks performed by a
is sometimes crucial to solving a crime. Plant fragments, seeds, pollen, and soil may be used to place a suspect at the crime scene. For example, pollen found on the clothing of a suspect can be matched to that of a rural crime scene, thus suggesting that the suspect was in the same area. Plant and pollen evidence also can reveal that a corpse has been moved. Find out more about forensic botany in
Coroners and medical examiners are charged with determining the cause and manner of death, overseeing the analysis of evidence, and presenting their findings in court. They often work with the police to help guide ongoing investigations by supplying them with the results of any forensic tests that have been performed. The responsibilities of these two offices cover every aspect of investigating a death.
The terms coroner and medical examiner (ME) are often used interchangeably, but they are, at least theoretically, quite different (see the following section for details). Regardless of which system is employed, in death investigations many of the duties of the coroner or the ME are similar. I use the term ME throughout the remainder of this book, even though some jurisdictions employ coroners for handling the legalities of death.
In the United States, two types of forensic investigative systems exist: the coroner system and the medical examiner system. Fortunately, the trend is toward the latter system, though it is far from perfect.
The coroner is an appointed or elected position that, unfortunately, requires no special medical or forensic skills. The sole criterion seems to be the ability of the person seeking the office to be elected or appointed. The coroner could be the sheriff, a newspaper publisher, a neighborhood café owner, or the local funeral director. They too often possess little or no medical training or experience.
During the past several decades, the politics of the office have evolved so that today many jurisdictions require the coroner to be a licensed physician. He may be an internist, an obstetrician, or a dermatologist but doesn’t necessarily have to be a pathologist and certainly not a forensic pathologist. Thus, the coroner may not actually be qualified to perform many of the duties of the office. This deficiency led to the creation of the medical examiner system.
In theory, a medical examiner (ME) is a physician licensed to practice medicine, and many are trained in pathology and forensic pathology, meaning that ideally they are medical doctors with special training in pathology and experience and training in forensic pathology. A forensic pathologist is a clinical pathologist who has taken extra forensic training. He usually heads up the crime lab and oversees all aspects of death and criminal injury. The heart of the forensic pathologist’s job is performing forensic autopsies, which are designed to help determine the cause and manner of death.
In an ideal world, every jurisdiction would have a medical examiner who also is a board-certified forensic pathologist, qualified to fulfill all the duties of his office. The world, as you know, is not ideal, and even today in many jurisdictions nonmedically trained coroners and MEs continue serving as local public officials charged with investigating death. This solution is a practical, money-saving one because these areas simply don’t have the population base to justify the presence of a forensic pathologist. Under these circumstances, the coroner/ME has several alternatives for acquiring the needed specialized pathological services.
If the coroner/ME is not a pathologist and not licensed to practice medicine, he must contract with larger regional or state medical examiner’s offices for pathological examinations and laboratory testing or hire a forensic pathologist to serve as an assistant coroner or medical examiner. Under the legal umbrella of the coroner’s or ME’s office, the assistant coroner then performs autopsies, testifies in court, and oversees the crime lab.
The duties of the coroner and ME are diverse, but many of them relate to the forensic investigation of death, including
Determining the cause and manner of death
Establishing the identity of any unnamed corpses
Estimating the time of death
Supervising the collection of evidence from the body
Searching for any contributory factors such as disease
Correlating wounds with the weapons that may have been used to inflict them
Certifying or signing the death certificate
In fulfilling these duties, the coroner or ME uses any and all available information. Reviewing witness statements, visiting crime scenes, reviewing collected evidence and the results of crime lab testing, and, if a pathologist, performing autopsies are part of this endeavor.
In addition, the coroner or ME performs other duties not directly related to death investigations. These include
Examining injuries of the living and determining their cause and timing
Providing expert testimony in court
Overseeing the crime lab (in some areas)
When faced with an unexplained death, the ME takes a systematic approach to evaluating the case. This approach is similar to the one taken by physicians who treat the ill. Good physicians take a complete patient history, perform a thorough physical exam, order appropriate laboratory tests, and make an informed diagnosis. Only after this process can treatment begin.
The ME, on the other hand, obviously cannot obtain a direct history from the deceased but nevertheless can obtain information from police reports, medical records, witness statements, and interviews with family members, law enforcement, and other medical personnel. To help gather the needed information, the ME may possess (in some jurisdictions) or receive subpoena power from the court and can therefore legally require someone to provide information or evidence such as a blood sample, fingerprint, or shoe impression.
If no evidence of any potentially lethal trauma is seen, the ME then looks for natural causes of death by reviewing medical records, perhaps discussing the death with the person’s physician or performing an autopsy when necessary. These investigations may lead the ME to conclude that the person died as a result of a natural cause, such as a heart attack, an infection, diabetes, or any number of other diseases.
When no natural cause is present or evident, however, the ME explores other manners of death, looking for less-obvious forms of trauma, poisons or drugs, or other signs of accidental, suicidal, or homicidal death.
After the analysis is complete, the ME files a report in which the essentials of the case are laid out and a conclusion is reached regarding the cause, mechanism, and manner of death.
The manner of death is an opinion expressed by the ME based upon all the circumstances leading to and surrounding the death. The ME’s opinion may or may not be accepted by the courts, law enforcement, attorneys, or the victim’s family. Even if the ME concludes that a death was a homicide, prosecutors may disagree and file no criminal charges. Likewise, surviving family members may sue the coroner’s office for any number of reasons to change the manner of death, particularly in situations in which the manner of death has been ruled a suicide.
The ME’s opinion is not written in stone and can change if new evidence comes to light that suggests a previously ruled natural death may not have been so natural after all.
The coroner’s technician is an extension of the coroner/ME and is indeed the ME’s representative at the crime scene and works with the ME at the morgue. These technicians are often the ones who actually deal with the body at any crime scene where a death has occurred.
As an extension of the ME, the technician has legal authority over the body. The crime scene may be the domain of the police and the criminalists, but the body belongs to the medical examiner.
The coroner’s technician may do the following:
Make a cursory examination of the body
Obtain a core (liver) body temperature, which is critical in determining the time of death (see
Direct the taking of photographs of the body
Collect any trace or insect evidence from the body
Wrap and transport the body to the ME’s office
The technician may also assist the ME in all the examiner’s duties at the morgue and may
Perform or help with the performance of autopsies
Prepare the autopsy report at the direction of the ME
Communicate with the public, the media, and law enforcement on issues relating to the medical examiner’s office
Explain the autopsy procedure and its results to family members of the deceased
Testify in court as the ME’s representative
After they have analyzed the evidence, members of the forensics team may be called upon to explain it in court. Expert testimony can often make or break a case, and experts — be they medical examiners, crime-scene investigators, toxicologists, or other key players — can be called to testify by either the prosecution or the defense. In turn, their testimony may be refuted by the testimony of experts with different opinions.
The sworn duty of the ME is to present the facts in court and offer an unbiased opinion based on those facts. She is solely responsible for presenting evidence in court because she is in many ways an officer of the court. The ME may ask a member of her staff or of the crime lab to present evidence, but the ME is the one who is ultimately responsible to the court.
The ME may be asked to discuss and explain the forensic evidence and render an expert opinion regarding the evidence to the judge and jury. In this regard, the ME acts as an educator as well as a scientist. The ME often is the only person from whom a jury hears complex scientific information presented in an understandable way. At other times, the ME must pit knowledge and communication skills against other experts with different opinions.
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