When a middle-aged mother began helping out at a Montreal elementary school, no-one turned a hair. But when parents found out about the woman’s past, their hair stood on end.

In the playground of a Montreal private elementary school, in Quebec, Canada, young pupils are gathered round, innocently petting a woman’s dog. The children’s parents mill about, oblivious to the dark secret lurking hidden in their midst. Somehow, one of the country’s most notorious criminals has inveigled her way into the daily lives of their offsprings.

Greaves Adventist Academy can trace its history back to 1899, when the English Church School was founded in the Montreal neighborhood of Notre-Dame-de-Grace. More than a century later, the area remains an important center of culture and commerce for the English-speaking residents of Canada’s second largest city.

The institution grew to become a leading educational facility with strong connections to the church. Having changed its name to Greaves Adventist Academy, in honor of Sylvia Greaves its longest-serving principal, the school nowadays teaches between 250 and 275 students, and it welcomes pupils of all faiths and none.

Until March 2017, life at Greaves was just like that of countless other schools across the world. Parents or carers would arrive to drop off or collect their children, and would often mingle with each other in the schoolyard. Some of them would also volunteer or be invited to take a more active role in the running of the school and its activities.

One of the parents trusted with such responsibilities was a 47-year-old blonde woman called Karla Homolka, who had three children enrolled at Greaves. Her volunteer work at the school was even said to have included accompanying a group of kindergarteners on an outing to the Montreal Science Centre.

As well as helping out, the parents and students of Greaves also knew the outwardly respectable middle-aged woman for another reason. Homolka owned an appealing dog, and often brought it along to the schoolyard where the children could pet it – reportedly, she even took the animal into the classroom.

It was also said that Homolka shared her handicraft skills with pupils, teaching knitting to them in class. On the surface, she appeared every inch the supportive mom, engaging fully in her children’s education. But it turned out that this seemingly innocent woman was hiding a terrible guilty secret.

In March 2017 an unidentified man began handing out leaflets to parents at the entrance to Greaves. Calling himself a concerned citizen he used the papers to spread the unbelievably vile – but perfectly true – story about Homolka. The school community descended into a state of shock.

Born on May 4, 1970, in Port Credit, Ontario, Homolka grew up as the eldest of three children. By all accounts, she was popular and pretty, with a passion for animals that led her to taking on a job in a veterinary clinic. Then, in October 1987, the teenager’s normal life came to an abrupt end with a chance meeting.

While attending a convention for pet lovers in Toronto, the 17-year-old Homolka met 23-year-old Paul Bernardo. She was instantly attracted to the handsome, fair stranger, and the pair immediately began a relationship. However, Bernardo’s charming exterior was masking something deeply sinister.

At the time, Bernardo was involved in a series of vicious sexually motivated crimes against young women and girls in his home city, Scarborough, to the east of Toronto. He would wait for his victims to disembark from local buses, then following his target until he could ambush and attempt to rape them. By the time he met Homolka, he had already attacked at least four females with increasing levels of violence.

But, rather than be repulsed by Bernardo’s crimes, Homolka appeared to approve. In fact, in December 1990, she allegedly assisted her boyfriend in drugging and raping her 15-year-old sister, Tammy, using sedatives from the clinic where she worked. During the assault Tammy tragically choked on her own vomit and died. Six months later, having been cleared of all involvement with the death, Homolka and Bernardo wed.

Over the following three years, the married couple lured at least two teenage girls – Leslie Mahaffy and Kristen French – to their deaths in what came to be known as the Schoolgirl Killings. Sadly, it seems more than likely that several more victims were attacked by the duo. Finally, in January 1993, the sadistic collaboration began to unravel.

After suffering domestic abuse from Bernardo, Homolka decided to leave her husband. Meanwhile, police began steadily closing in on the man they had dubbed the Scarborough Rapist. Knowing that if he was captured, it would only be a matter of time before her own crimes were uncovered, Homolka went to the police. She told them Bernardo was guilty of the rapes and murders, and that he had abused her and forced her to assist him.

In light of these claims, Homolka was offered a plea bargain by prosecutors and eventually sentenced to just 12 years for manslaughter in the cases of Mahaffy and French. However, video evidence later emerged which appeared to show Homolka had been far more involved in the murders than she had initially claimed. Canadian press subsequently called the plea bargain, a “Deal with the Devil.”

Despite the controversy surrounding the case, Homolka was released from prison in 2005 in the full glare of the media spotlight. Moving to Quebec province, she married again, to her defense lawyer’s brother, Thierry Bordelais, and went on to have three children. Two years she left the country, keen to escape further press attention.

Intrepid journalists managed to track Homolka to the Antilles in the Caribbean, where she was spotted in 2012. Then the trail seemed to go cold – until the leaflets began to appear at Greaves Adventist Academy. Apparently, Homolka had moved to Chateauguay, an island suburb of Montreal, and begun sending her children to the exclusive school.

Unsurprisingly, parents at the $6,000-a-year institution were horrified about the hands-on role that the notorious criminal appeared to be taking at the school. “It’s really unacceptable,” mother Stephanie Deligne told the Montreal Gazette newspaper in May 2017. “My daughter was playing with the dog of Karla Homolka, and I was right next to her, but I didn’t know who she was.”

Some experts have even gone so far as to suggest that Homolka presents a danger to the children at Greaves. One – a lawyer representing the bereaved Mahaffy and French families – believes that her psychopathic tendencies could be triggered again. The school, meanwhile, has defended its actions.

According to a spokesman for the Seventh-day Adventist Church, which administrates Greaves Adventist Academy, Homolka is not a regular volunteer at the school and is never allowed unsupervised contact with the pupils. However, these assurances seem to have done little to allay the fears of the parents concerned. “We don’t want her here. How would you feel knowing that your child is interacting in person with a serial killer?” one told local news magazine show Breakfast Television Montreal. “It’s not right.”