Post-mortem examinations have confirmed that two bodies discovered in the Canadian wilds are those of the teen murder suspects who apparently took their own lives after weeks on the run, police have announced.

"The two died in what appears to be suicides," federal police said in a statement.

Kam McLeod, 19, and Bryer Schmegelsky, 18, who were wanted over the murders of an Australian man and his American girlfriend, as well as of a Canadian university professor, had led police on a cross-country manhunt.

Initially, the pair were reported missing themselves after their car was found burned out in British Columbia province, but police then discovered the third body, and the teens were named as formal suspects.

Last week, police closing in on the pair had found items linked to the suspects on the shores of the Nelson River. They also found a battered aluminum boat.

Their remains were soon found in dense brush in the central province of Manitoba about 8km from a burned-out stolen vehicle belonging to one of the victims, discovered on 22 July.

It is unclear when exactly the pair died.

However, police said there are "strong indications" that they had been alive for a few days since last being seen near the town of Gillam, Manitoba, which had sparked a massive police search of the area.

Police deployed tracker dogs, a drone and search planes equipped with infrared cameras to comb the difficult, forested and swampy terrain, which was infested with mosquitos and home to bears and wolves.

Investigators and the police behavioral analysis unit are also continuing to try to piece together the events that lead to the murders. Their findings are to be released in the coming weeks.

McLeod and Schmegelsky, who were childhood friends, had led police on a more than 3,000km chase halfway across the vast country to Manitoba province.

They had been wanted over the murders of Australian Lucas Fowler, 23, and American Chynna Deese, 24, who were discovered shot dead on 15 July along a highway in British Columbia.

Mr Fowler had been living in British Columbia, local media reported, but the pair had been travelling extensively. Ms Deese's family told US media that the couple had embarked on a road trip through Canada.

Authorities then found the body of 64-year-old Leonard Dyck, a botany professor at the University of British Columbia, on 19 July.

RCMP Assistant Commissioner Kevin Hackett has said it would be "extremely difficult for us to ascertain definitively what the motive was".

In an interview last month with the Canadian Press as the manhunt ramped up, Schmegelsky's father said his son was deeply troubled and had never recovered from his parents' divorce in 2005.

"He's on a suicide mission," Alan Schmegelsky said.

He said in an interview with Australia's "60 Minutes", which ran on Sunday, that "his troubles are over. I'm so sad that he felt that he had to take this road trip".

"I'm so sorry for what's happened," he said, but added in defence of his only son: "I'm not going to say my son is a murderer until I get some facts."

Kennedy Deese, sister of one of the victims, dismissed his comments, saying in a Facebook post: "Your sorrow is for yourself. You cannot relate to us, as we had no doings in the cause of your pain, when you've played a part in the cause of our pain.

"To the murderers and their family, the appropriate action when mistakes are made is taking responsibility. The proper public response would have been a genuine apology. But we still forgive you and have mercy."