A woman whose daughter was murdered 20 years ago says that her journey to forgiveness was an important and necessary step to continuing on with her life.

Lesley Parrott's 11-year-old daughter Alison disappeared from her home in July 1986 after receiving a phone call to meet someone for a photo shoot. She was found two days later in a densely wooded area near a Toronto subway station. She had been raped and strangled.

Parrott discusses the forgiving process she has experienced over the past two decades on "Forgiveness: Stories For Our Times," a documentary that will air on CTV on Saturday.

"It is an enormously complex topic and yet somehow if you can't contemplate forgiveness in whatever way that moves you, it becomes very difficult for you to move forward," Parrott told CTV's Canada AM. "I think the film is about people finding a place and a way to move forward and that of course means coming to terms to some extent with the person who killed their loved one."

Ten years after Alison's death, Francis Carl Roy, a man with a lengthy criminal record was arrested. DNA evidence found in Alison's body linked him conclusively to her death and he was convicted of first-degree murder. Roy's family approached Parrott to convey their sympathy over Alison's death.

"I felt that took a lot of courage on their part to come and just offer their condolences and I thanked them for it and I thanked them for their courage," Parrott said. "Because that must have been tough. It was still one human being to another...I was very touched by it actually."

The documentary also features others dealing with the murder of loved ones and relatives. Alan McBride, whose wife was killed in an IRA bombing and Reverend Julie Nicholson, whose daughter was killed in the 2004 London subway bombings, are not yet able to forgive.

However, Anne Marie Hagan, a woman whose father was murdered by the family's next door neighbour and Parrott, say they are able to forgive those who are guilty.

Parrott believes this decision has helped her to accept the reality of her daughter's death.

"It just becomes part of you, it's not so much a matter of going back when you've processed it and lived with it so much it becomes part of you. I actually don't find it particularly hard," Parrot said.

"I live a very full and very involved life, so by no means would I say I am stuck, but Alison's life and Alison's death is just so much part of who I am it's just there and accessible.

"And if in my sharing it can give some other people some hope that after this horror you can go on and live a fairly joyful life albeit always with some sadness, then I think that's really worth doing."

The documentary "Forgiveness: Stories For Our Times" airs on CTV on May 26. Check your local listings for more details.