DNA evidence has led police to lay charges against a man in relation to a violent assault and robbery 39 years ago in Edmonton.

John Edward Beausoleil, 66, was arrested in his home in Orilla, Ont., on Feb. 26 and charged with rape and robbery.

Historical crimes investigators came across Beausoleil's name a year and a half ago while developing a DNA profile of a suspect.

Using the national DNA data bank and the known offender bank, the profile was matched to Beausoleil.

It means Beausoleil had previously been ordered by a judge to submit his DNA.

Police say they were unable to identify a suspect in 1981, but that DNA testing has improved in the years since.

"Even when testing didn't develop a profile in 2005, there's going to be opportunities moving forward as those thresholds drop that we can revisit that with testing through the labs," explained the section's Staff Sgt. Ryan Tebb.

However, Tebb noted, police's ability apply those methods to cold cases still hinges on whether certain evidence was collected at the time of the crime.

"Just the nature of how we did business and unawareness of forensics at that time – DNA was just kind of emerging in that time period, so saving exhibits from that wouldn't have been common," Tebb said.

"Fortunately, this case did."

On. Sept. 18, 1981, a 36-year-old woman told police she was accosted by a strange man while in a parkade and sexually assaulted. He fled from the Lancaster Terrace area with her purse.

Beausoleil would have been 27 years old at the time.

"We're certainly being mindful of Mr. Beausoleil's potential criminality in our area," Tebb told med.

"As we review our files, being mindful that he was active in 1981."

Beausoleil has been brought back to Edmonton.

Tebb said Edmonton Police Service's historical crimes section has been bolstered over the last five years, allowing for a review in 2016 of 2,400 historical sex assaults and homicides. Investigators parsed the files down to a caseload of 259, which were assessed for "solvability."

The oldest homicide case is from 1937, though the recent arrest represents the oldest case in which charges have been laid.

Police have made their way through the top third of the cases, Tebb said.

"We in our historical crimes section, we're still looking at these files…

"We are actively trying to pursue and trying to bring some closure onto these files."