Forensics For Dummies. Douglas P. Lyle

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.

       Determining who did what where

      

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.

Chapter 2

      Getting to Know the Forensics Team

       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.

Gathering the Evidence: The Criminalist at Work

      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:

      ✔ Crime-scene investigator: 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. Chapter 5 gives you the skinny on fingerprints.

      ✔ Firearms examiner: The duties of this individual include examining and identifying firearms, comparing bullets and shell casings, and searching for and identifying gunshot residue. Chapter 18 gives you the details.

      ✔ Tool-mark examiner: 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 Chapter 7.

      ✔ Document examiner: 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 Chapter 19 for more.

      ✔ Trace evidence examiner: These specialists analyze and compare hair, fibers, glass, soils, and paints to determine their type and origin. Chapter 17 tells you more about analyzing trace evidence.

Looking into the CSI Effect

      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