The question of what happened to Theresa Allore has haunted her family since the 19-year-old, a student at Champlain College in Lennoxville, disappeared in November 1978.

Allore's body was found on the edge of the Coaticook River near Compton on April 13, 1979. Her remains were in poor shape.

At first, police called it a probable drug overdose. Later, a coroner ruled she had probably been strangled.

Now, 38 years later, Quebec provincial police are re-examining her case. Allore is first on the Sûreté du Québec's list of cold cases – more than two dozen people missing and believed murdered since 1977.

The body of Theresa Allore. She was found in her underwear by a passing trapper. (Submitted by John Allore/Allo Police archives)

Her brother John, who was just 14 when Theresa Allore disappeared, has spent years piecing together his own files on his sister's death, even creating a blog devoted to the investigation and other unsolved Quebec cases dating back to the same era.

CBC News spoke to John Allore about the investigation that he considers botched by police – and his suspicions his sister may have been the victim of a serial killer.

Theresa Allore, with her brother John, at their home in Pierrefonds. (Submitted by John Allore)

The disappearance

Friday night, Nov. 3, 1978: It had been a warm, dry day in Lennoxville. At Champlain College, students were preparing for the weekend.

Theresa Allore turned down offers from friends, telling them she was going to study. Allore lived in a residence about eight kilometres from the main campus. There was a bus, but if students missed the last bus, many hitchhiked.

Did Allore hitchhike that night?

Another girl told a detective hired by Theresa's family that she had seen her in the residence at 9 p.m., but Theresa did not show up later that night to hang out, as promised, with two other girls.

John Allore has come up with many theories.

There had been a series of sexual assaults on campus that fall: Was Theresa a fatal victim?

The man in charge of her residence was never questioned by police, but he left his job a short time later. The school closed the residence, even though there was a housing shortage at the time. Why?

Allore says there are still a lot of questions – questions not asked by police at the time.

The missing person's notice put out by police after Theresa Allore's disappearance. (Submitted by John Allore)

Botched investigation?

Allore is glad to see his sister's case is being reinvestigated. But he realizes it is the coldest of cases.

After four decades, whoever was responsible is at least in his 60s — perhaps even dead. Anyone who might have seen anything may also be long gone.

In 2001, Theresa Allore's family approached police to try to obtain her clothing and any other possessions found with her remains.

John Allore says his father was given Theresa's jewelry and was told there was nothing else. He believes her clothing and other material evidence have all been destroyed — even though the circumstances of her death are unsolved.

"What's going on here?" Allore asked. "Over a span of 40 years, police have systematically engaged in the destruction of case evidence."

A police sketch of the area where Theresa Allore's body was found: on the edge of a pond near the Coaticook River. Theresa's body is marked with an X. (Submitted by John Allore)

SQ won't comment

Police would not confirm what happened to that evidence, and even today, the SQ will not comment on the details of Theresa Allore case.

"It's still an ongoing investigation," said an SQ spokeswoman, Lt. Martine Asselin.

Asselin says Allore's case is still being treated as a suspicious death, not a homicide.

That's despite the findings of the coroner, Michel Durand, who concluded in his April 1979 report that marks found on Theresa Allore's body "could have been marks of strangulation."

Serial killer theory

Allore now considers himself to be an expert on Quebec crime, especially 1970s murders. He says he sees the same mistakes over and over again: botched investigations, lost or destroyed evidence, leads not followed.

Allore believes at least one, maybe two, serial killers were operating in Montreal and the Eastern Townships at the time of his sister's death.

"It was good hunting grounds," Allore says. "You had a bunch of students, young adults in CEGEP, all isolated in that one area."

"If you read the history of sexual assaults on women in the Lennoxville area in that time, it's well documented, and it's quite horrendous."

Theresa Allore in her family's kitchen. She was 19 when she disappeared. (Submitted by John Allore)

Slim chance of success

So many years after Theresa Allore's disappearance, her brother is realistic.

"The prospects of solving such an old cold case are slim, if you don't have evidence, if you don't have a confession, if you don't have a witness," he says.

He has his own theory about the killer.

"I think it was a crime of opportunity," he said. "I think she was either stalked or somebody very impulsively took the opportunity of picking her up."

"At some point, an advance was made, she resisted, and they strangled her to death. And they dumped her body a mile away from where she was living in Compton, Quebec."

You have to accept sometimes, he said, that "this one can't be solved. And that's hard especially when it's something that's so personal."

He hopes, at least, he can effect change, and he tries to be satisfied with "the idea that I will continue to push to get some systemic change in Quebec law enforcement."