The mother of a gunman who shot and killed 14 women at a Montreal university will be sharing her personal story on the upcoming anniversary of the 1989 massacre.

Monique Lépine is participating in a church ceremony on Dec. 6, 20 years after her son stormed Montreal's École Polytechnique and gunned down 14 engineering students before killing himself.

At the church ceremony in Laval, Lépine will name the 14 women her son Marc Lépine killed "so that we can think about the families that have been suffering from this crime that my son did," she told CBC News.

"It's my way of saying to the people that I'm very sorry for what my son did to them, and all the consequences that happened in their lives."

Lépine was a reticent figure in the immediate years following her son's killing rampage now known as the Montreal Massacre.

"You know, the shock, the denial, the emotions that are involved in something like that" made it virtually impossible for her to reach out to others, she said in an interview on Wednesday.

She hid her grief for 17 years, living in isolation and shame until she accepted "the fact that you cannot change these things."

And then her desire to speak out was sparked by the 2006 shooting at Montreal's Dawson College — where one student was killed and 19 were injured by a gunman.

In 2008, Lépine released a book called Aftermath, chronicling her grief about her son. Since then, the retired nurse has told her story to church groups, schools, and even in prisons, as a volunteer with a federal restorative justice program.

Lépine believes her unique perspective and experience allows her to be less judgmental with inmates.

"We don't raise children to become killers, you know, but sometimes it's out of our control," she contends.

Lépine has met with the family of at least one of her son's victims, an experience she called liberating.

A private, closed-door ceremony will be held for the families of the Polytechnique victims at a hall on campus Sunday.

Dec. 6 is now Canada's national day of remembrance and action on violence against women. Ceremonies will be held across the country to mark the event.