As an investigative tool, DNA has been a powerful weapon in identifying or confirming who committed a crime. But the value of DNA evidence is overshadowed by regular stories of corruption, incompetence, and flawed interpretation. It’s, for this reason, I never accept the DNA results as golden for the prosecution in a contested case.
Here’s another story. http://www.miaminewtimes.com/news/hundreds-of-south-florida-cases-in-doubt-over-dna-testing-problems-9383687
Two linked issues are driving the ongoing saga. The first came to light last summer, when an investigation found problems with how the Broward Sheriff’s Office crime laboratory was interpreting complex samples, which contain DNA from more than one person. With its accreditation threatened, the lab last July ceased reporting those complex samples and instead began sending them to outside experts.
BSO lab officials downplay concerns, insisting their methods have repeatedly been validated and their analyses and protocols are sound. The lab’s methods would “never produce a false identification,” says Col. Steve Kinsey of the Broward Sheriff’s Office.
Keep in mind that USACIL has not been immune to problems with their examiners, although it has been some time since the biggest scandal.