Analyzing the Evidence: Forensic Science

The first forensics lab in the United States opened in 1923 in Los Angeles. In 1932, the FBI established its own forensics lab to serve police departments and other investigating authorities all over the country. The FBI lab is one of the largest in the world.

The Denver Crime Lab at the Colorado Bureau of Investigation provides evidence collection and laboratory analysis for any police department in Colorado that requests its services. It also conducts state investigations that don't fall under the jurisdiction of any local authority.

Some specialty departments in the Denver Crime Lab include:

• Latent fingerprints and impressions
  Develop latent fingerprints; analyze and compare fingerprints, footwear and tire impressions; run fingerprints through the Automated Fingerprint Identification System (AFIS, which utilizes the FBI database) for comparison against hundreds of millions of prints

  CBI technicians use these camera setups to photograph recovered prints to use in comparison and for running through the AFIS system. On the left is an old-school Polaroid setup, and on the right is a digital-camera setup. Mr. Clayton prefers the Polaroid results.

• Trace evidence
  Run GSR analysis; identify and compare samples of soil, glass, fibers and paint
• Chemistry
  Conduct analysis and comparison of illicit drugs, explosives and unknown chemicals
• Computer Crimes
  Recover evidence from computers; perform computer enhancement on audio or video evidence
• Firearms and toolmark identification
  Identify firearms; test firearms to establish barrel pattern and distance of gun from entrance wound; identify and compare bullets, casings and toolmark impressions
• Serology and DNA
  Conduct body fluid analysis, including DNA analysis for blood stains, semen and hair for identification and comparison

  Comparison microscope setup in the CBI serology lab

• Questioned documents
  Detect forgery and alterations; conduct handwriting comparisons; reconstruct destroyed documents; identify and compares printers, typewriters or copiers used to produce a document

Often, a piece of evidence passes through more than one department for analysis. Each department delivers a complete report of the evidence it analyzed for the case, including the actual results (numbers, measurements, chemical contents) and any expert conclusions the scientists have drawn from these results. The CSI in charge might compile the results and deliver them to the lead detective on the case, or the lab might send the results directly to the detective squad.

On the Stand The role of a crime scene investigator doesn't end when he completes his evidence report. It doesn't even end when the lab results related to that evidence are delivered to the detectives on the case. A big part of a CSI's job is testifying in court about the evidence he collected, the methods he used to recover it and the number of people who came into contact with it before it ended up as the prosecution's Exhibit D. And the defense attorney's job is to attack the evidence, which sometimes means attacking the person who collected it. This is why search warrants, evidence logs, photographs and extremely detailed reports are so critical to the CSI process. The defense will try to get every piece of incriminating evidence thrown out of court. The legality of the search, the untainted preservation of the evidence and the full, undisputable documentation of the crime scene are prime considerations in a crime scene investigation.

CSI vs. "CSI"

Photo courtesy HSW Shopper

So, does Hollywood get it right? When asked if the TV show "CSI" accurately depicts his job, Joe Clayton's short answer was, "No." The long answer was that the show does accurately represent certain aspects of crime scene investigation, but it leaves a lot out and it adds a lot because, well, it's Hollywood. Viewers don't want to watch a bunch of CSIs waiting around for a search warrant, and they would probably be unsatisfied if they never got a look at the suspect.

Scientifically speaking, "CSI" sometimes misses the mark. In reality, it's not possible to come up with a two-hour range for the time of death. Also, you don't just scan a fingerprint into a computer and wait for it to spit out a photo of the suspect. Fingerprint-comparison software returns several possible matches that an expert then analyzes visually to determine a definite match.

Other places where Hollywood gets it wrong involves investigative process. Crime scene investigators almost always get warrants before searching a scene. Pretty much the only scene that might not require a warrant is an apartment owned by the victim, who lived there alone and never shared the space with anyone else at any time. This means there's a lot of waiting involved -- it's pretty unusual for a CSI to arrive on a scene and just start searching. What usually happens is the CSI arrives and determines which areas need to be searched, and then someone gets a hold of the district attorney, who gets a hold of a judge, who signs whatever search warrants are requested. Once the district attorney brings the warrants to the scene, the search begins.

And the search involves the evidence, not the neighbors of the victim. CSIs do not deal with witnesses or suspects. They don't interview people at the scene, they don't interrogate anyone and they definitely don't pursue the perpetrator. These are all the jobs of the detectives on the case. Also, it's rare for a CSI to handle an entire investigation from beginning to end, even if we're just talking about the evidence. There are tons of people involved in collecting and analyzing evidence, including CSIs, forensic specialists, medical examiners and detectives. It's a rare CSI who has the time or expertise to do it all.

In Mr. Clayton's opinion, shows like "CSI" aren't making criminals any smarter. The truth is, crime scene investigation and forensic science are always trying to catch up with the criminals, not the other way around. And while there are certainly people who meticulously plan a crime and how to get away with it, Mr. Clayton's experience with crime scenes tells a different story: Most violent crimes are committed in the heat of the moment. The perpetrator is in an agitated state, possibly under the influence of drugs or alcohol, and doesn't have the presence of mind to meticulously cover his tracks. It's the rare criminal genius who studies forensic science so he can commit the perfect murder and get away with it.

For more information on crime scene investigation, forensic science and related topics, check out the links on the next page.

Becoming a CSI CSIs work long hours, must be available for emergencies 24/7 and often deal with gruesome scenes. For Joe Clayton, his job as a CSI involves constant reminders of man's inhumanity to man. But he views his job as a chance to use science to help people. CSIs can be police officers or civilians. The most common way to become a CSI is to become a police officer first and then receive CSI training. All police departments and law-enforcement agencies have different criteria. Typically, a civilian CSI should have a two- or four-year degree. Mr. Clayton is not a police officer. He graduated from college with a bachelor's degree in biology and minors in chemistry and behavioral sciences. He applied for a CSI position at the Kansas Bureau of Investigation and received his training there. Call your local police department or crime lab to find out what their requirements are for civilian CSIs. Before deciding to pursue the job, you should visit a morgue and have a look at a mangled body -- if you pass out, consider another career.