Some of the region’s top crime scene investigators pulled back the curtain and allowed media to look at an increasingly important part of their job.

Police have been collecting DNA evidence for almost two decades but it is being used more widely today than anyone could have predicted.

Collecting evidence at crime scenes is grim work. More often than not, the search includes looking for traces of DNA.

Valerie Blackmore is a forensic biologist who trains police officers on what to look for and how to collect DNA, including samples unseen.

“Now we can get DNA profiles, usable DNA profiles from blood stains or biological material that you can’t even see,” says Blackmore.

Blackmore is teaching police officers from all over the Maritimes about the latest collection and lab techniques.

Police in Saint John normally use DNA evidence a few dozen times a year and not just for high-profile crimes, such as the Richard Oland murder case; sometimes DNA testing is conducted at the most routine crime scenes.

“Very, very common to be looking for DNA at a break-and-enter scene,” says Sgt. Mark Smith. “They’ve taken an item out of the fridge and taken a drink from it, so saliva is a factor there.”

Frequently, DNA testing is being used to clear the wrongly convicted, like Nova Scotia’s Gerald Barton, who was wrongfully convicted of statutory rape in 1970.

“Gerry never would have been cleared without DNA,” says Barton’s lawyer Dale Dunlop. “It proved conclusively that he was not the father of the child and that, in turn, made the complainant admit that she lied.”

In that way, Smith says DNA results can work for both the Crown and defence.

“It’s not my job to get a conviction. It’s my job to go to a crime scene and do the best I can in collecting the evidence and presenting that in court,” says Smith. “If it results in a conviction, so be it. If it results in exoneration, that’s great.”

Smith says police are also facing the so-called CSI effect, where juries may come to court expecting to see DNA evidence. If they don’t, police now need to explain why DNA is not part of the case.

With files from CTV Atlantic's Mike Cameron