Faulty Forensic Science

Forensic science uses scientific principles to inform criminal investigations. Faulty forensic science is the second-greatest contributor to wrongful convictions overturned through DNA testing.1 Roughly half of wrongful convictions overturned through DNA testing included faulty forensic science. DNA, genetic material unique to each person, has been used since the late 1980s to identify perpetrators of crime and to exonerate the innocent. DNA testing techniques have been validated and improved over the years through extensive scientific research. In contrast, there is not sufficient research to validate many other forensic approaches—including analyses of hair, fiber, bite marks, firearm and tool marks, and shoe prints. Even forensic techniques that have solid research support may not be conducted, interpreted or presented properly.

A Sample Case

NCIP exoneree George Souliotes spent 16 years in prison after he was wrongfully convicted of arson and triple murder. In 1997, his rental property burned to the ground in the middle of the night and three tenants died in the fire. Based on burned holes in the floor, burn patterns and deep charring, investigators determined that the fire had been deliberately set. The prosecutor’s case against Souliotes included testimony by forensic arson analysts and evidence of a flammable substance found on Souliotes’ shoes and in the fire debris. During the first trial, the defense brought in an expert who testified that a faulty stove with a history of leaking gas was the likely cause of the fire. The first trial resulted in a hung jury.
In the second trial, the defense did not bring in any experts or other witnesses to counter the prosecutor’s case, and Souliotes was convicted and sentenced to three life terms without parole. When NCIP attorneys got involved in the case, they discovered new evidence discrediting the faulty forensic analysis that got Souliotes convicted. The federal district court found compelling evidence of innocence based on the faulty fire science, unreliable eyewitness identification and ineffective assistance of counsel and ordered a retrial. Ultimately, the State of California conceded that it could not prove the fire was deliberately set, and Souliotes was released from prison after his attorneys negotiated an agreement to secure his freedom.

Policy Reform

In 2009, the National Academy of Sciences issued a report2 on forensic science-based on studies funded through the Science, State, Justice, Commerce, and Related Agencies Appropriations Act of 2006.3 The report noted that the forensic sciences have contributed valuable evidence to criminal justice, but that faulty forensic science testimony has led to wrongful convictions. The report recommended ongoing advances in the field to increase law enforcement accuracy in identifying perpetrators and to reduce the likelihood of wrongful convictions.

Efforts to prevent wrongful convictions caused by faulty forensic science include support for standards in each forensic discipline and for increased funding for research. Enforcement mechanisms are also needed to ensure that the standards are followed. Professional accreditation can improve the quality of forensic analyses, including crime lab work. Ongoing funding for DNA testing is also critical to identify actual perpetrators and prevent and rectify wrongful convictions. Statewide forensic science commissions can provide oversight and help secure funding. California does not currently have such a commission.

In April 2015, the FBI announced that at least 90 percent of trial transcripts, analyzed through a multi-agency review4 of federal cases, contained erroneous testimony regarding hair analysis. These disturbing findings highlight the need for extensive review of state cases where hair analysis testimony helped secure the conviction. Statewide review of hair analysis cases has begun in several states, including Florida and Texas. NCIP supports efforts to conduct a statewide review of hair analysis cases in California.

¹ See “Unvalidated or Improper Forensic Science,”
Available at:

² Committee on Identifying the Needs of the Forensic Sciences Community, National Research Council. Strengthening Forensic Science in the United States: A Path Forward. Washington, D.C.: National Academy of Sciences, August 2009. Available at:

³ H.R. Rep. No. 109-272, at 121 (2005) (Conf. Rep.).

⁴ The review was a joint effort of the U.S. Department of Justice, the FBI, the Innocence Project and the National Association of Criminal Defense Lawyers. See the Innocence Project’s press release, available at: