The two teenagers suspected of shooting dead Australian tourist Lucas Fowler and his US girlfriend Chynna Deese on a Canadian highway left a "last will and testament" video message.

Key points: Kam McLeod and Bryer Schmegelsky were found dead in bushland in remote northern Canada on August 7

Kam McLeod and Bryer Schmegelsky were found dead in bushland in remote northern Canada on August 7 They had been on the run for more than two weeks after being suspected of murdering three people

They had been on the run for more than two weeks after being suspected of murdering three people There are hopes the video could possibly explain the motives of the two teenagers

Kam McLeod, 19, and Bryer Schmegelsky, 19, recorded the video message on their mobile phones before taking their own lives in remote bushland in northern Manitoba, the Toronto Star reported.

About 30 seconds of the video was shared with family members of the former fugitives.

The video could be the key to explaining why the two teenagers, who weeks before were working at Walmart, would suddenly become killers.

The Royal Canadian Mounted Police are reportedly in possession of the full video recording.

Australian Lucas Fowler and his girlfriend Chynna Deese were found dead in Canada. ( Supplied: NSW Police )

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Mr McLeod and Mr Schmegelsky, from Vancouver Island, were found dead in bushland near Gillam, Manitoba, on August 7.

The Royal Canadian Mounted Police announced on August 12 that autopsies pointed to the teenagers taking their own lives.

The police did not comment on the video and suggested more details would be made available in the coming weeks, according to Canadian broadcaster CTV.

Two guns were found with the bodies and are undergoing forensic analysis to determine if they are the weapons used to shoot Sydney man Mr Fowler, 23, and Ms Deese, 24, from North Carolina, dead on the side of a British Columbia highway on July 15.

The couple's Chevrolet van had broken down, leaving them stranded in an area with minimal mobile reception.

Mr McLeod and Mr Schmegelsky are also suspected of killing 64-year-old university botany lecturer Leonard Dyck four days later on another BC highway.

The teenagers drove Mr Dyck's Toyota RAV4 3,000 kilometres east to Gillam, sparking a massive manhunt that eventually led to their bodies.

AAP/ABC