Teen Murderers Went On Random Killing Spree Before Filming Confession And Dying In Suicide Pact

The mystery of why two teenage friends went on a random killing spree in northern Canada that claimed the lives of Australian tourist Lucas Fowler, his U.S. girlfriend and a university lecturer has been revealed.

The Royal Canadian Mounted Police held a press conference on Saturday morning detailing the "random crimes of opportunity" that had no real motives.

Kam McLeod, 18, and Bryer Schmegelsky, 19, shot and killed Lucas Fowler and girlfriend Chynna Deese on July 15 after finding the couple and their broken-down van on the side of an isolated highway in northern British Columbia.

They then shot and killed 64-year-old University of British Columbia botany lecturer Mr Dyck four days later, stole his Toyota RAV4, set their own Dodge pick-up truck on fire and sparked a nationwide manhunt.

READ MORE: 'He Was A Superhero': Friends Remember Murdered Australian Lucas Fowler

"Significant work has been done to answer the many questions," Assistant Commissioner Kevin Hackett said.

Canadian police have concluded that the shootings were random and the teens had planned to kill more people before agreeing on a murder-suicide.

"There's no indication these were planned or predicted," Commissioner Hackett told reporters in Vancouver.

Police revealed that McLoed shot Schmegelsky before shooting himself.

The teenagers were found dead on August 7 in bushland more than 3000km east near the northern, desolate Manitoba town of Gillam.

Assistant commissioner Hackett said police found a digital camera on the duo.

"It contained six videos and three still images," he said.

In the video, the pair admitted to the killings and voiced the desire to kill more people. They also said they planned on hijacking a boat and going to Europe or Africa.

Lucas Fowler and girlfriend Chynna Deese

READ MORE: Father Accused Of Seeking 'Fame' From Son's Alleged Murder Spree

The video showed "no remorse for actions and intentions to kill others," Hackett said. It also included requests from the teens to be cremated.

Authorities said families had been notified of their findings before publicly releasing them.

The video will not be released to the public because it  "may influence or inspire others ... essentially creating copycats."

"They were cold, they were remorseless," Commissioner Hackett said.

160 police officers worked on the investigation and worked through 1500 tips from the public.

Fowler is the son of NSW Police chief inspector Stephen Fowler.

NSW Police sent two homicide detectives to Canada to assist the investigation, liaise and support family members.

The couple's van had broken down and RCMP assistant commissioner Kevin Hackett said McLeod and Schmegelsky targeted them for "unknown reasons".

Chynna Deese's family released a statement describing her as "a ray of sunshine, and for her to be taken has made the world feel a bit darker."

"The loss we continue to endure is shattering, but Chynna's memories are a benediction to her genuine happiness and intense love of life," they said.

If you need help in a crisis, call Lifeline on 13 11 14. For further information about depression contact beyondblue on 1300 22 4636 or talk to your GP, local health professional or someone you trust.

With AAP.