Canada's most prolific serial killer will appear in front of a parole board at a prison north of Montreal on Tuesday in a bid to be set free.

Clifford Olson has spent almost 25 years behind bars for abducting and murdering 11 children and teens in British Columbia in the early 1980s.

In 1982, Olson pleaded guilty to 11 counts of murder and was given 11 life sentences. He's now eligible for parole.

Families of Olson's victims have come to Quebec to give impact statements at the hearing at the Sainte-Anne-des-Plaines Institution.

'It changed our lives'

In spring of 1981, Daryn Johnsrude, 16, ran an errand for his mother at the corner store near his home in Coquitlam, B.C. He never came back.

Daryn's battered body was found a month later. He had been sexually assaulted and murdered. The teen was Olson's third victim. Olson went on to kill 11 children.

"It was the beginning of a terrible nightmare. It changed out lives. Totally," said Gary Rosenfeldt, Daryn's stepfather.

Over the years, Rosenfeldt has channeled his grief and anger through a support network he runs from Ottawa, called Victims for Violence.

But he fears he won't be able to avoid the pain of reliving his loss at Olson's parole hearing.

Rosenfeldt says he hasn't slept much in recent days.

"It's going to tear my heart out... to watch my wife and daughter give victim impact statements. He's going to laugh and snicker while this is going on," Rosenfeldt predicts.

Rosenfeldt is outraged Olson is even getting a chance to make a case for freedom.

"We did away with capital punishment in this country. I can live with that. But I cannot live with a system that allows dangerous offenders back into the community," Rosenfeldt said.

Federal Justice Minister Vic Toews says the government is considering changing parole procedures for offenders such as Clifford Olson.

Until that happens, his victims' families will have to go through this process again, in two years' time.