The chief coroner on Prince Edward Island says his office hasn't completed its investigation into the murder-suicide of a mother and her son in St. Felix this past June.

RCMP released autopsy and toxicology results on Wednesday showing Patricia Hennessey, 37, and Nash Campbell, 4, had prescription drugs in their systems when they died of smoke inhalation in a burned-out vehicle in St. Felix.

Police said their investigation is complete, but Dr. Charles Trainor says his office has yet to see the autopsy reports and hasn't yet decided whether to call for a coroner's inquest.

"The purpose of an inquest is who, where, when and by what means did so-and-so die. And the most important thing is, how can we prevent deaths of this nature from occurring in the future? That's something that really needs to be worked on," he said.

"I think you haven't heard the last of this investigation."

The bodies were discovered on June 21 after the firefighters found a Jeep Wrangler engulfed in flames.

Sources have confirmed to CBC that Hennessey lost custody of her son the day before.