In many felony cases that are tried in Pittsburgh courts, prosecutors present DNA evidence to the jury. Due to the popularity of television shows that feature forensic scientists, people often are impressed by such evidence because it appears to narrow down the number of people who could have committed the crime to the defendant.
But recent scandals involving crime labs around the country put in doubt the trust prosecutors expect us to have in their forensic results. The cases involve lab workers failing to follow proper procedures when testing the genetic materials, leading to questionable results and possibly causing the wrong person to be accused.
In 2012, a former chemist for a state narcotics analysis lab in another state admitted that she rarely followed necessary procedures. The chemist was known for working very quickly, often churning out more than 500 samples per month, as opposed to the average number of 50 to 150 per month. Her "methods" for being so fast often involved skipping steps such as using a microscope. More than 1,000 people who were convicted based in part on the chemist's dubious conclusions could have their convictions overturned.
In a more recent case, a technician with a medical examiner's office is accused of failing to detect biological evidence in at least 26 rape kits. In seven cases, full DNA profiles were developed despite the missed evidence, possibly implicating the wrong person. As in the earlier case, the revelation is leading to a comprehensive review of the technician's work to determine how many more errors she made.
Cases like these indicate why evidence presented by the prosecution is not necessarily beyond challenge by the defense, even evidence purported to be scientifically proven.
Source: Slate, "The Unsettling, Underregulated World of Crime Labs," Justin Peters, Jan. 14, 2013
· Our law firm provides legal defense for those facing federal charges. For more information, please visit our Pittsburgh federal charges page.