The Flaws In Forensic Science

In 1996, four small pieces of fiber played a critical role in the investigation of the abduction and murder of 16-year-old Sofia Silva. After the evidence was processed in Virginia’s crime lab, the fibers led investigators to Karl Michael Roush who was eventually charged with the crime.

But when two more girls were kidnapped and killed, the FBI conducted a DNA test on the fibers and discovered that it was an incorrect match.

“It was only by that testing that the defendant, the original man charged with Sofia Silva’s case, was released,” Betty Layne DesPortes, the president of the American Academy of Forensic Sciences and a criminal defense attorney, said in a recent interview with Science Friday. The real killer was later tracked down in 2002.

The mismatched fibers in the Silva case are just one example of faulty science in forensic investigations. In 2015, the FBI admitted that for decades investigators have overstated the accuracy of hair sample matches over 95 percent of the time with the evidence often favoring the prosecution. Other evidence, such as patterns and impressions like bite marks and blood spatter, have been used as proof beyond a reasonable doubt in court in the past, but have little scientific backing—and, as the Silva case shows, have even led to wrongful convictions.

“Law enforcement has relied on these disciplines for so long, and they believe in them,” said DesPortes. “It’s very difficult for them to appreciate the fact that, because they did not arise in science—like DNA and some of the other chemistry disciplines did—that these techniques lack some of the validation studies necessary to prove their worth and their reliability.”

The 2016 report by the President’s Council of Advisors on Science and Technology revealed that there is a lack of empirical studies to support the validity of current practices. It follows the 2009 National Academy of Sciences report that criticized the scientific rigor and reliability of forensic science in the United States’ justice system.  

During the Obama administration, forensic scientists from federal and independent laboratories, lab directors, attorneys, and judges came together to form the National Commission on Forensic Science. The commission made recommendations that would set long-term standards to help ensure forensic scientists provide accurate statements on the witness stand. However, in April, Attorney General Jeff Sessions decided to not renew the commission, leaving some uncertainty on the future of reforming and providing resources to forensic science.

There is a “big disconnect that has led people to believe that forensic science is fine—it’s in good shape, it’s funded, it’s supported—when in fact it’s not,” Suzanne Bell, a forensic and analytical chemistry professor at West Virginia University who served on the now defunct National Commission on Forensic Science, told Science Friday when reached by phone. “If we’re not going to cough it up for justice, what are we going to cough it up for?”

[‘Bones’ inspires a new generation of crime fighters.]

The misconception has risen in part by the pristine, futuristic labs portrayed on television shows like CSI and NCIS. Over the course of a single episode, multiple forensic scientists work together on individual cases, finish tests, and analyze evidence in a matter of hours. It may build suspense and add to entertainment but in reality, “forensics labs are the bottom of the budget barrel,” said Bell, who has helped the producers of CSI with an episode that involved extracting a corpse from a tar pit. The labs at the state and local level (where most of the forensic science happens) are particularly underfunded, she said.

“If we’re not going to cough it up for justice, what are we going to cough it up for?”

“There are newer, better, and faster ways to do things, and it’s not that labs don’t want to do it. They just don’t have the time and they don’t have the money,” she said. “These folks are working just to clear backlogs every single day.”

Labs are made up of scientists from different disciplines—from forensic chemists who run DNA analysis to forensic entomologists who look at insects to help estimate time of death. In some cases, scientific discourse was applied forensically. Not all of them, particularly pattern-matching disciplines, arose from an academic field.  

“Disciplines, like firearm, toolmarks, latent prints, were developed principally in the law enforcement arena,” Bell said during the Science Friday interview with DesPortes. “Doesn’t mean they’re not valid, but they really have a different heritage to them.”

[Forensic entomologists hunt down insects to help catch criminals.]

The developers of these disciplines set the standards, however the accreditation never underwent independent, unbiased scientific scrutiny. That allows for instances of circular validation where an expert examiner may use a technique to identify a suspect and then later use that same technique to convict a suspect, explained DesPortes.

An additional issue, lawyers or jury members prefer definitive answers that scientists cannot  always give. For example, discharge residue from a gunshot can provide useful information, but an expert witness must be careful in a testimony, Bell said. If particulates are found on a suspect, it may not mean that he or she fired the weapon.

“We can’t give [lawyers] that answer. We can say we found particulates that are consistent with gunshot residue, which can mean they were either close to it or they discharged the weapon,” Bell told Science Friday on the phone. “There have been cases in Europe in particular where very small numbers of particulates were used ultimately for false convictions.”

“You see on TV where suspects get the Miranda warnings, you have the right to an attorney, if you can afford one or not. But you don’t have the same right to scientific review.”

Wrongful convictions may also occur due to the inability to review or understand the scientific evidence. Before the FBI stepped in to the Silva case, Roush, an indigent defendant, asked the court to appoint an expert to review the case, but his request was denied.

“You see on TV where suspects get the Miranda warnings, you have the right to an attorney, if you can afford one or not,” said DesPortes. “But you don’t have the same right to scientific review.”

In Bell’s lab at West Virginia University, scientists review reports and explain the information to different clients. However, for the vast majority of cases, people do not get this opportunity, said Bell. The National Commission on Forensic Science brought this literary deficiency to light.

The 2009 National Academy of Sciences report recommended that the government institute a federal-level agency that would be responsible for forensic science—allowing it to be independent from both the prosecution and defense as well as law enforcement. Bell agrees that the next best step for forensic science is to “move away from law enforcement and become a science.”

[Behind the scenes at the New York City morgue.]

Since the 2009 report, progress has been made with the help of the National Commission on Forensics. During its two years of existence, the members created 43 documents on certification requirements for examiners and laboratory accreditation. These initial changes will improve the quality of the work as well as catch malfeasance in laboratories, explained DesPortes.

But with the end of the commission, many question how to address the serious issues that still persist within the field. Experts in forensic science will have to continue to push independently for improvements in standardization, said DesPortes.

Forensic science “is an area where we want to move forward,” said Bell. “And we need cooperation from all parties, from law enforcement on up.”