Canadian police say they have concluded Kam McLeod, 19, and Bryer Schmegelsky, 18, died by suicide.
Autopsies confirmed have two bodies discovered in the Canadian wilds were those the of the teen murder suspects wanted over the killing of Australian Lucas Fowler, his girlfriend and another man, who apparently took their own lives, police said Monday.
"The two died in what appears to be suicides by gunfire," Royal Canadian Mounted Police announced in a statement on Tuesday.
Kam McLeod, 19, and Bryer Schmegelsky, 18, wanted over the murders of Sydney-man Mr Fowler and his American girlfriend, as well as of a Canadian university professor, had led police on a national manhunt.
Previously, the RCMP were tight-lipped about details surrounding the autopsies on Schmegelsky and McLeod and an item of interest was found near their bodies.
It is unclear when exactly the pair died, but 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.
The Royal Canadian Mounted Police (RCMP) said they are conducting a forensic analysis of two firearms located with the teens in order to confirm that these were used in the British Columbia murders.
Schmegelsky and McLeod, from Vancouver Island, are suspected of shooting dead Mr Fowler, 23, and his North Carolina girlfriend, Chynna Deese, 24, after the couple's van broke down on a British Columbia highway on 14 July.
Four days later on another BC highway Schmegelsky and McLeod were accused of murdering 64-year-old botanist Leonard Dyck, stealing his Toyota RAV4 and driving it 3000km east across northern Canada until dumping and burning the vehicle outside the small town of Gillam, Manitoba.
A massive manhunt was launched in the area, involving police and military units.
It ended last Wednesday when the fugitives were found dead in thick scrub 1km from the banks of the Nelson River, near Gillam.
The RCMP has not revealed how Schmegelsky and McLeod died or what the item found in the vicinity was.
The announcement follows the airing on Sunday in Australia of 60 Minutes' interview with Schmegelsky's father Alan, who apologised to the families of the victims.
Mr Schmegelsky, however, was shown cheering and saying "kudos, boys" when told during the interview the teenagers had successfully passed through a police roadblock.
He said the breakdown of his marriage led to his son becoming "angry".
Earlier, in an interview last month 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," he said.
Investigators and the RCMP behavioural 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 3,000-kilometer chase halfway across the vast country to Manitoba province.
RCMP Assistant Commissioner Kevin Hackett has said it would be "extremely difficult for us to ascertain definitively what the motive was."
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.
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