Monday, Oct. 27, 2025, marks 50 years to the day a troubled high school student in Ottawa murdered a neighbour at his home and then opened fire on his packed religion class, ultimately killing one classmate. In the leadup to the anniversary, CBC spoke to survivors of the school shooting to find out what happened in the days and decades that followed. (Videography and editing by Mathieu Deroy. Production design by Michel Aspirot.)

The survivors of one of Canada’s first school shootings, 50 years later

Warning: This story discusses school violence, sexual assault and suicide.

Ten years ago, Dennis Curley went back to what he calls "the scene of the crime" — back inside Classroom 71 of his Ottawa school.

The St. Pius X High School alumnus was on a personal mission, bent on getting his life back.

For decades, Curley was gripped by nightmares about Oct. 27, 1975, the day a severely troubled classmate named Robert Poulin opened fire on their packed religion class with a shotgun bought at Giant Tiger.

It was one of Canada's first school shootings, and helped pave the way for new federal gun control measures. But it was only one half of what made that day so awful.

That morning, Poulin raped and murdered a neighbour and aspiring doctor, 17-year-old Kim Rabot, who was a student at Glebe Collegiate Institute. He then biked to St. Pius, wounded several more students, and killed himself in the hallway with the gun.

Mark Hough, an 18-year-old with plans to attend law school, was among those injured. While everyone else in Classroom 71 recovered — physically, at least — Hough died in hospital over a month later.

Kim Rabot, left, and Mark Hough, right, were the victims of the Oct. 27, 1975, murders committed in Ottawa by Robert Poulin. (CBC/Hough family)

Curley, now in his 60s and a psychotherapist, is thankful "there is no white line around my body," as his professional profile page states.

But Curley struggled for years to understand how "a good man" like Hough could be killed while "a jerk like me" kept on living.

He finally sat down with his own psychotherapist and hit upon the idea of going back to the classroom.

So that's what Curley said he did on Oct. 27, 2015, with the school principal guiding him by the arm.

When it came time to leave Classroom 71, however, Curley froze, seized by the memory of opening the door in 1975 and seeing Poulin's body.

He then fell to his knees and began to cry.

A police officer stands outside Classroom 71, in the hallway where Robert Poulin shot himself, on Oct. 27, 1975. (City of Ottawa Archives, Ottawa Journal, 028383)

'Stories are lost if they're not told'

Curley did manage his way out of the classroom, and in the 10 years since, he says he hasn't had a bad dream about the shooting.

"When we face our fear, we're set free. We bury the fear? We're in bondage," he says.

All that being said, Curley doesn't necessarily recommend everyone follow in his footsteps.

"You have to decide that for yourself," he says.

Dennis Curley, a survivor of the 1975 shooting at St. Pius X High School in Ottawa, stands outside the school on Aug. 5, 2025. 'I have relived that day my entire adult life,' Curley says. (Guy Quenneville/CBC)

The October 1975 shooting at St. Pius, along with the equally shocking murder of Kim Rabot, was a transformative event for Ottawa in its time.

But in the last half-century, the city's collective memory of that moment has faded — while those deeply affected have each wrestled and coped with the aftermath in their own ways.

In this concluding chapter of a four-part series examining the murders' painful legacy — which began by looking at the events in full before focusing on the tragically short lives of Rabot and Hough — CBC is now turning to the St. Pius survivors to hear about the shooting, its impact, and the days and decades that followed.

Several declined to be interviewed, saying it would be too difficult.

"E very time I think back to that day, I plummet into a depth of sorrow and I do not want to experience this feeling," wrote Lori Mladek, a Classroom 71 student at St.