The decision to hold on to video and photographs of Russell Williams' crimes raises the risk that the evidence could some day leak out, warns the lawyer who represented the families of Kristen French and Leslie Mahaffy.

Crown Attorney Lee Burgess said Thursday that Williams' Nissan Pathfinder will be destroyed, along with stolen underwear and zip ties he used to bind his victims.

But for now at least, the video footage and photos he took of his crimes will be put under lock and key at OPP headquarders in Orillia in case they are ever needed by a Parole Board.

Timothy Danson, who represented the families of the two girls murdered by notorious sex killer Paul Bernardo, questioned that decision.

"The risk of these getting out in the future is very, very real," he told CTV's Canada AM.

"I know with the Frenches and Mahaffys the only way they could guarantee their daughters would never be violated again was to destroy the videotapes."

Danson said transcripts and descriptions of the videos and photographs are sufficient for any Parole Board purposes in the future.

Williams, former commander of CFB Trenton, was sentenced Friday to two life sentences with no chance of parole for 25 years. He had pleaded guilty to two counts of first degree murder charges, two counts of sexual assault and dozens of break and enters and thefts.

Danson said he believes Williams belongs in a category with Canada's worst offenders, and said the evidence presented in court will ensure he never receives parole.

"I'm sure (the families) are relieved that he has pleaded guilty and will spend the rest of his life in jail," Danson told CTV's Canada AM on Thursday.

"Yes he's eligible for parole in 25 years but in my view he's in the category of Paul Bernardo and Clifford Olson, he's never getting out, but it was important nevertheless for the Crown to establish a full and fulsome evidenciary record so that the Parole Board will have this to ensure he never gets out."

Danson compared the Williams proceedings to the trial of Bernardo, who was convicted in 1995. Bernardo pleaded not guilty, which is why a lengthy trial was necessary and all evidence had to be presented in court, including pictures and videos of violent and gruesome sexual crimes.

The timeline was also much different. Because of Williams' guilty plea, his hearings only lasted four days -- the time it took to read the charges, register a plea, read the agreed statement of facts, hear the victim impact statements and hand down the sentence.

A trial would have likely lasted years due to Williams' many crimes and the sheer amount of evidence in police' possession, Danson said.