Articles Posted in DNA

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Popular crime shows would have you believe that the analysis of forensic evidence is the key to finding the perpetrator of a crime. But is forensic evidence reliable?  DNA evidence, blood spatter patterns, bite marks, finger prints and other common types of forensic evidence have been subjected to scrutiny and some just don’t hold up. For example, I previously wroteabout an innocent man who spent 33 years in prison based on bite mark analysis – a forensic evidence technique that has been discredited in the scientific community but continues to be used by prosecutors.

Similarly, other forensic analysis methods have been questioned, or even debunked, by science but continue to be an important part of the prosecution’s arsenal. In the popular imagination, these techniques provide a slam-dunk conviction. But most members of the public, from whom a jury of peers is selected, would be surprised to learn—and perhaps even reject—the proposition that quite often forensic evidence is nothing but junk science. Overcoming this bias takes the persuasive skills of criminal defense attorney who is up on the science and can communicate a reasonable doubt about the forensic evidence.

Here’s one that may surprise the average reader: Even positive DNA evidence may not be evidence at all. The common assumption is that if a suspect’s DNA is found on the victim or at a crime scene, the suspect is positively implicated in the crime. But that is not always true. Often the DNA evidence is in trace amounts but is thought to be conclusive evidence of the suspect’s presence at the scene. DNA analysis has become so sophisticated that forensic technologists can pick up even the smallest amounts of DNA. The problem is that humans shed DNA all the time and everywhere. When you touch anything, you will leave your DNA. Another person touching the same object can then pick up your DNA. This is referred to as the “touch-transfer” property of DNA. So, imagine that you took a public bus. Another passenger on that bus picked up your DNA and shortly thereafter committed a crime. Your DNA may very well show up in forensic analysis, implicating you in the crime.

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The Brave New World of Law Enforcement Investigation

The digital age has changed everything in the world around us and law Enforcement is no exception. Back in the old days, police investigation procedures were limited to talking with potential witnesses, taking lots of photographs, lifting fingerprints, forensic analysis of blood, and that sort of thing. Now law enforcement has investigation tools that make their job easier and make it harder for the criminal to “get away with it.” But these tools present their own dangers to the public. As civil rights advocates warn, the brave new world of law enforcement tools endanger our civil liberties. I will discuss why this may be so in my next post but today, let’s review just a few of the new age law enforcement tools.

We might begin with DNA analysis, which was no doubt the first huge law enforcement tool of the digital age. We are all familiar with DNA analysis, but it’s pretty amazing to think that it has only been around since the mid-1980s. DNA has proven to be a very effective law enforcement tool and on the flip side, DNA evidence techniques have freed individuals who were wrongly convicted of a crime.

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33 YEARS IN PRISON FOR A CRIME HE DID NOT COMMIT

Imagine you are a 26 years old sailor docked at port. A murder and brutal rape is committed in the city where your ship is docked. The rape victim cannot identify her assailant but she does describe him as wearing a sailor’s uniform bearing the same insignia as your company. DNA samples are collected from the rape victim and a bite mark on her leg is photographed. The police investigation focuses on your ship and dental records are collected of all the sailors whose uniform carries the insignia identified by the victim. Your dental records apparently lead the police to suspect you and you are required to provide a dental impression. A forensic odontologist then identifies your teeth as the same teeth that left the bit mark on the victim’s leg. Despite your protestations of innocence, you are tired and convicted of the crime purely on the expert testimony that the bite mark was yours. You receive a life sentence.

During the ensuing years, you challenge the verdict in the appellate courts, staunchly maintaining your innocence. And indeed you are innocent of the crime!

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