Criminal Forensics: Not So Fast…


la-me-ln-oj-simpson-case-knife-dna-test-20160307One of the reasons I started writing crime fiction twenty years ago was my fascination with criminal forensics. Like everyone else in the country, I was glued to the TV during the OJ Simpson trial. Apart from my surprise at his acquittal, I was introduced to a brave new world. Prior to the trial I had no idea law enforcement could analyze blood spatter, or shoe prints, or what the direction of knife wounds could say about the perpetrator. It was a revelation that eventually led me to writing.

However, twenty years later you’d be forgiven for thinking law enforcement has at its disposal a trove of rock solid, scientifically proven tools that reveal criminals’ guilt beyond any doubt. The truth is dramatically different. Polygraph testing has long come under fire for being unreliable; criminal profiling has been criticized as no better than guesswork; and some say forensics is in crisis as more tools, methods and systems turn out to be less than trustworthy.

One of the problems is that forensic science was not developed by scientists. It was developed by law enforcement, by applying “common sense.” But as more criminal cases unravel, the lack of good science is seen as a primary cause.

Unreliable Polygraphs

According to the American Psychological Association  the psychologist Leonard Saxe, PhD, believes that ‘The idea that we can detect a person’s veracity by monitoring psychophysiological changes is more myth than reality’. He said it back in 1991, so the technology has been questioned for some time.pic08

The APA says:

“A particular problem is that polygraph research has not separated placebo-like effects (the subject’s belief in the efficacy of the procedure) from the actual relationship between deception and their physiological responses. One reason that polygraph tests may appear to be accurate is that subjects who believe that the test works and that they can be detected may confess or will be very anxious when questioned. If this view is correct, the lie detector might be better called a fear detector.”

Despite that, FBI agents still take regular Polygraph tests as part of the agency’s internal security protocol. That’s not to say nothing is being done. Some researchers recommend factoring in extra indicators like heart rate and skin temperature. Others are looking closely at tech like functional brain imaging to help measure deception, but there are questions about its effectiveness as well.

On the bright side, our court system, including the Supreme Court, has rejected polygraph evidence because it’s inherently unreliable. But polygraph testing is still used to screen personnel, establish if suspects and witnesses are telling the truth, and to monitor those on probation.

Criminal profiling guesswork

pic08In 2008 a review article by Snook, Cullen, Bennell, Taylor and Gendreau criticized criminal profiling. Called The criminal profiling illusion: What’s behind the smoke and mirrors?, it outed profiling as a pseudo-science based on flawed assumptions. The article maintained that criminal profiling is based on a set of psychological theories that were disproved during the 1960s, so-called trait theory. As the Debunking Denialism website says:

“In some areas, such as physical attributes, profilers managed to out-compete the non-profilers. In other areas, such as cognitive professes, offense behavior and social history, the non-profilers performed better than profilers. Overall, profilers had a slight advantage.”

If you were on the jury of a criminal case, would a “slight advantage” be enough to make you trust a profiler’s verdict beyond reasonable doubt? The article even compares its credibility to that of astrology.

Bite marks, blood spatter and more coming under fire

When a forensic dentist claimed seven bite marks found on a dead body were ‘entirely consistent’ with dental impressions taken from a suspect, the police thought they’d got their man. Even though the tooth marks were the only physical evidence tying the suspect to the murder, the jury convicted him of second-degree murder and he was sent to prison for 25 years to life. Fifteen years later DNA tests proved the man innocent fifteen years later and set free. It might seem like a glitch. But over 200 innocent people have had their convictions overturned and in 50% of the cases poor forensic analysis helped send them to prison. Forensic dentistry is just one of the methods being questioned.

The scientific veracity of bite marks, blood-splatter patterns, ballistics, hair, fibers and handwriting analysis, even fingerprint tech, are all under scrutiny, but they’re all used by police. According to law professor Michael Saks from Arizona State University, in an article on the Popular Mechanics website,

“As you begin to unpack it you find it’s a lot of loosey-goosey stuff.”

What does the future hold?

A growing number of experts are demanding reforms. In 2005, Congress commissioned the National Academy of Sciences to explore forensics in US law enforcement. The resulting ‘blistering’ report revealed ‘serious deficiencies’ and suggested extensive reforms. And it made it clear that DNA is the only forensic discipline that has so far been proven “with a high degree of certainty”.

Hopefully the questionable methods will eventually be improved so they are more accurate. Or new methods will be developed and old ones dropped altogether. Until then, whether you’re innocent or guilty, this is not a great time to be dependent on the criminal justice system.

Unless you’re O.J.