In an apparent bid to avoid missing a six-year statute of limitations, the Wisconsin Department of Justice recently filed felony charges against a man who mailed a threatening letter to a judge in 2012. Prosecutors apparently obtained DNA from the back of the stamp, which the suspect had presumably licked.
The basic science behind DNA testing is sound enough. Each individual has DNA that varies as much as one person varies from another. With the right technology, we should be able to compare a DNA sample found at a crime scene with one taken from a suspect.
Recently, investigators in California arrested a suspect in the "Golden State Killer" case. Joseph James DeAngelo, a former police officer, is accused of murdering as many as 13 people and raping 50 women during the 1970s and 1980s.
We have written extensively on this blog and elsewhere about faulty forensic science contributing to wrongful convictions. Numerous instances of crime lab scandals between 2000 and 2008, including multiple instances of fraud and error, resulted in Congress funding an in-depth investigation and review of the forensic science disciplines and related forensic laboratory practice.