NOTRE-DAME-DES-PRAIRIES, QUE. -- A Quebec man accused of killing his two three-year-old boys before taking his own life had been arrested for harassing the mother of the children just days before the tragedy, a friend of the suspect says.

The body of Ian Lamontagne, 46, was found with those of his two kids, three-year-old Antoine and Tristan Lamontagne, in Notre-Dame-des-Prairies, Que., northeast of Montreal, on Saturday.

Quebec provincial police declined to offer further details Monday. But Patrick Boucher, who says he was friends with Lamontagne for six years, said the suspect was arrested on Wednesday for harassing the mother of the two kids. Lamontagne was released shortly after his arrest, Boucher said.

"What he told me is that he got arrested for criminal harassment while he was heading to his former partner's place," Boucher said in an interview Monday.

Police have refused to comment on the case, and Audrey Roy-Cloutier, spokeswoman for Quebec's prosecution service, said her agency has no information on Lamontagne's arrest.

However, a source at the prosecutor's office who was not authorized to speak publicly said that when someone is arrested and released with a promise to appear in court, their case file is likely not yet in the hands of prosecutors. Under those circumstances, the source said, police wouldn't send the file to prosecutors until the investigation is complete.

Quebec's police watchdog -- Bureau des enquetes independantes -- said it was notified of the case by provincial police but is not investigating because it doesn't believe the deaths fall within its mandate.

A spokeswoman for Quebec Public Security Minister Francois Bonnardel declined to comment on the matter.

Boucher called the murder of children a "horrible, unacceptable, unforgivable act," and said he would like discussion of the three deaths to "focus on how a human being who loves his children can go from mode 'I love my children' to 'destroying my children's lives."'

"How can we transform this event into something more?" Boucher asked. "To learn how, how should I react to my other friends who tell me they're having difficulties?"

The mayor of Notre-Dame-des-Prairies said in a statement that the tragedy has shaken the community and left behind unimaginable pain. Suzanne Dauphin said the killings show that mental-health problems can strike anyone, and she encouraged people to take care of their loved ones if they show signs of psychological distress.

- This report by The Canadian Press was first published on Aug. 28, 2023

   -- By Jacob Serebrin and Thomas MacDonald in Montreal.