Advances in DNA technology are guiding police departments in Tampa Bay to identify suspects from small and dated samples. That’s helping law enforcement close cases that have been on the books for decades.
On June 15, a DNA match led the St. Petersburg Police to charge Anthony Stokes with a sexual assault they say he committed 32 years ago.
Now, they are using his genetic information to investigate if he was a part of other crimes during the 1980s.
Dr. Bryanna Fox is an assistant professor in the Department of Criminology at the University of South Florida. While familiar with how St. Petersburg Police handles cold cases, Fox is not involved with the Stokes investigation.
However, the former special agent in the Federal Bureau of Investigation said that in 2006, Congress allowed for a wider range of searchable DNA profiling using a nationwide database. Before, only convicted felons were entered.
Now, the database includes people arrested for various felonies and people with different job positions. Fox said that created over a million new profiles for departments to search through and compare crime scene DNA with.
The last time Stokes’s DNA was tested was in 2006, before those new profiles were added to the database.
“It could be the case that when all of these new profiles were added in about 2008 or later, one of these profiles was the offender, and now that they retested it again, it matched,” said Fox.
Another possibility, according to Fox, is that DNA testing methods have improved. Previous efforts needed a large amount of quality DNA for conclusive matches.
“Now, with advances they can do slightly decomposed DNA, or they can do small amounts of it, or sometimes both, and they can still get a good result back and they can do it in a shorter amount of time,” said Fox.
Either way, the improvements in both the database and the technology should help investigators.
“I do think it’s going to be more and more common for law enforcement to go back and review these cold cases. St. Pete is certainly leading the way,” said Fox. “I’ve been down in their cold case unit and I know that the detectives and Major Shannon Halstead are working extremely hard going through every single page of every single cold case to try to see if there’s any evidence that they can retest.”
Fox said that a lot of police departments have underfunded and understaffed cold case units, and that it’s difficult for cold cases to be top priority.
“I think more and more agencies are going to start catching on, and doing the same exact thing and sending more cases out for retesting,” said Fox. “Through these advances that we’ve seen, and the larger number of profiles that are included in various open source or federal databases, I think they’re going to be more and more successful in the future.”
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