Coroner Yvon Garneau said it's likely the kids' father set fire to the truck using propane tanks from his barbecue, possibly as part of a copycat murder-suicide.
Garneau found Florence Houle, 2, and Zachary Houle, 8, died by asphyxiation from the fire in St-Edmond-de-Grantham, near Drummondville, Que. A third sibling, a six-year-old brother, was injured but survived.
The body of the children's father, Martin Houle, was found the next day by hikers in a nearby wooded area.
Houle was suffering from a series of financial hardships and conjugal strife stemming from his separation from his spouse, the coroner said.
During that time, in May 2011, Quebec media were devoting near daily headlines to the double-murder trial of former cardiologist Guy Turcotte, who admitted he killed his two young children during a period of marital breakdown but denied intent or pre-meditation. Turcotte also tried to kill himself, but failed, and was found not criminally responsible for the deaths.
Garneau said Monday that the media need to show restraint when reporting on family violence and infanticide, because coverage can prompt copycats.
"It risks giving ammunition to another person in the same situation," Garneau said.
Some killers also thrive on the public attention, he warned.
"We were giving publicity to a killer, and that's often what they're seeking — attention, publicity."
Media should show restraint, coroner says
In his recommendations, Garneau suggests to the Quebec Press Council that "the broadcasting of news about domestic disputes be restrained and pertinent, while respecting the public's right to information."
"There's often a copycat effect in these types of situations," he said.
Psychologist Suzanne Léveillée of the University of Quebec at Trois-Rivières said people suffering from the extreme stress of a marital breakdown and custody battles over their offspring can sometimes be influenced to act out by what they see in the news.
"In this period of severe fragility, which can last several days to several months, it's quite possible they become influenceable by the comments of people around them," she said, "including notions and events like domestic disputes playing out in the media."
Garneau is the same coroner who recommended last year that drivers under 24 years old not be allowed to get behind the wheel between midnight and 5 a.m., following a drunk-driving crash the year before that killed four young men.