A five-part Chicago Tribune investigation of forensics in the courtroom has revealed that flawed testing analysis, questionable science once considered reliable, and shoddy crime lab practices can often lead to wrongful convictions. Developments in DNA technology have helped shed new light on these problems by revealing the shaky scientific foundations of techniques like fingerprinting, firearm identification, arson investigation, and bite-mark comparison. A review of 200 DNA and death row exonerations nationwide in the last 20 years found that more than a quarter (55 cases with 66 defendants) involved original forensic testing or testimony that was flawed. Through hundreds of interviews, an examination of thousands of court documents and an analysis of criminal cases that turned on forensic evidence, the Chicago Tribune reporters discovered the following:
- Fingerprinting is so subjective that the most experienced examiners can make egregious mistakes.
- Forensic dentists, who link suspects to bite marks left on crime victims, continue to testify despite having no accepted way to measure their rate of error or the benefit of peer review. DNA has shown that even the field’s leading practitioners have made false bite-mark matches.
- Scandals at labs across the country — including facilities in Maryland, Texas and Washington state — have spotlighted analysts who have incorrectly assessed evidence, hidden test results helpful to defendants and testified falsely in court. These scandals underscore the often-ineffective standards governing crime labs. Analysts involved in faulty forensic work often testify in hundreds of trials, an indication of how widespread this problem can be.