Forensic Evidence: Not What It Used to Be

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Scientific evidence sometimes used to prosecute, and convict, men and women accused of crime has been glamorized by the true crime craze and the proliferation of television crime dramas.

Although some modern scientific breakthroughs have revolutionized prosecutions, and exonerations, scientific evidence is not new.

One might think that scientific evidence exists in every case; it doesn't. Most cases are solved by eyewitness identification — although not without its own problems — video evidence and talkative perpetrators.

As far back as 1855, authorities in Mississippi attempted to use hair samples that allegedly "matched" the hair of a murder suspect. A 2016 article in the Virginia Law Review by Chris Fabricant and Tucker Carrington revealed that the hair-matching conviction was ultimately overturned by a Mississippi Supreme Court.

The FBI ushered in the modern era of hair analysis in the 1970s and then struck a death blow to hair analysis 40 years later. Prior to 2000, according The Marshall Project in conjunction with Reason, hair microscopy was used in more than 20,000 cases, with experts testifying at times that a hair sample found at crime scene "matched" that of the suspect.

Countless men and women went to prison based on what, according to The Marshall Project and Reason, was "beyond the limits of science."

In 2015, the FBI admitted that nearly every examiner in its hair and fiber unit had given "flawed testimony."

Even so, hair samples have remained an important investigative tool. A hair sample may be a source of DNA helping to identify an assailant. Recent development in hair analysis may reveal the recent travel of an individual or the use of drugs or ingestion of poisons.

However, hair sample analysis is not the only form of widely accepted forensic evidence that has come under scrutiny. According to the University of Michigan's National Registry of Exonerations, there have been 3,466 exonerations nationwide since 1989. Those exonerations have enabled investigators and scientists to look back and examine the evidence used to convict innocent people. It is astonishing what the research has revealed.

Things like tool marks — "scientific" evidence used to match an object with the markings at the crime scene — are really not science at all. Bite marks used to put people on death row cannot be scientifically verified. Eyewitness identification is not the gold standard of identification it was thought to be; even fingerprints are not infallible.

Former United States Supreme Court Justice William J. Brennan Jr. wrote in a dissenting opinion more than 35 years ago, "There is almost nothing more convincing than a live human being who takes the stand, points a finger at the defendant, and says, 'That's the one!'"

Hundreds of studies on eyewitness identification have been published in professional and academic journals. One study by University of Virginia Law School professor Brandon L. Garrett found that eyewitness misidentifications contributed to wrongful convictions in 76% of the cases overturned by DNA evidence.

Fingerprint identification came under scrutiny in 2004. The FBI publicly acknowledged the fingerprint misidentification of an Oregon lawyer wrongfully implicated him in a terrorist bombing in Madrid.

Since then, the Department of Justice has begun research to set standards for the analysis of fingerprints. As part of that process, the FBI has implemented "blind verification" of analysis by agents unfamiliar with initial examinations.

Through a study conducted in 2004, cognitive neuroscientist Itiel Dror found that otherwise competent and well-meaning experts were swayed by what they knew about a case submitted for fingerprint analysis. Dror's study demonstrated that if an analyst knew that the suspect confessed or was arrested, the analyst's findings could be influenced. Cognitive bias seeped into the process even with the best trained experts.

Evidence once thought reliable has been challenged in courtrooms across the country. Blood-spatter patterns, arson analysis, firearm analysis — staples of the American criminal justice system have all come under scrutiny, and rightfully so. Nothing is more unjust than locking away an innocent person.

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Matthew T. Mangino is of counsel with Luxenberg, Garbett, Kelly & George P.C. His book "The Executioner's Toll, 2010" was released by McFarland Publishing.

Previously:
• 01/22/24: Doing Time Without Committing a Crime