Mystery surrounds the brutal murders of a young experienced Australian traveller and his US college sweetheart on a lonely stretch of highway in the far north of Canada’s British Columbia region.

The bodies of Lucas Fowler, 23 and his girlfriend of two years, Chynna Deese, 24, were found on Monday near the blue minivan they were driving on the Alaska Highway, 20 kilometres south of Liard Hot Springs.

The pair were just days into another adventurous road trip after meeting in a Croatian youth hostel in 2017. Authorities are yet to piece together why Mr Fowler, the son of a NSW police officer, and Ms Deese were targeted or if their shooting deaths were a “crime of opportunity”.

A third body has been found but while authorities are “looking at all of the leads”, they are not linking the latest discovery to the mysterious shooting murders of the young couple.

The body of a man was found on Friday near a burning pickup truck south of the Stikine River Bridge on Highway 37 in northern British Columbia, about 750km away from the Australian and his girlfriend.

“Northern BC is a really big area and yet they don’t have a lot of these events,” Royal Canadian Mounted Police corporal Chris Manseau told AAP on Saturday.

“Two of them have happened within a couple of days of each and people want to speculate.

“The last I heard there was nothing to tie either of those two together although investigators are looking at all of the leads.”

Suspicions of a serial killer heightened after Ms Deese’s family read of a maniac said to be prowling the Alaska Highway. These fears were dismissed by the Royal Canadian Mounted Police, who are leading the murder investigation.

“At this point there’s nothing to indicate that these rumours are true,” RCMP Sergeant Janelle Shoihet told reporters on Saturday (AEST).

“We recognise this news is troubling for the entire community and absolutely appreciate there are concerns for safety in an area that is popular with nature enthusiasts and tourists.

“This investigation is in its very infancy and it is not yet clear whether Lucas and Chynna were targeted or is this was a crime of opportunity.”

‘Something happened on that road’

Curtis Broughton, a mechanic, and his wife, Sandra, were among the last people to see the couple alive on Sunday afternoon about 3.20pm, sitting in armchairs on the side of the highway having their lunch. Mr Broughton stopped to help after noticing the van had broken down.

But after a quick chat with Mr Fowler he realised the young Australian had the problem under control and they headed home.

“He seemed like he had everything diagnosed properly,” Mr Broughton said.

“The vehicle was flooded out and they were going to try and get it going again until they could get the parts they needed.”

When he later heard the couple had been found dead, he contacted police: “Something happened on that road, some sort of conflict”.

Ms Deese’s brother, British Deese, told the Charlotte Observer their bodies were so badly beaten the family was told an open casket would not be allowed at his sister’s funeral, three days having been required to identify the bodies.

Mr Deese told the Observer that Mr Fowler, who had recently got a job on a cattle ranch, and his sister were “deeply in love”. He had stayed with the family for three months late last year and was considered a member of the family.

Mr Fowler’s father, Stephen, the chief inspector for Sydney’s north-west Hills district, and other family members including his mother and siblings have embarked on the long flight to Canada “to be with our boy and to bring him home”.

NSW Police Assistant Commissioner Mark Jones told reporters in Sydney on Saturday that the whole family is “absolutely devastated”.

He said two homicide detectives, including Detective Chief Inspector Wayne Walpole, would act as family liaisons.

“The RCMP (Royal Canadian Mounted Police) are an outstanding organisation, we have the utmost confidence in their capacity and capability to run this investigation but our commissioner has made a great decision to send over two officers … purely to assist the families,” he said.

“Just breaking down some of the communication and just really keeping us appraised and them appraised of what’s going on.”

Their bodies were found in a secluded area almost 1900km, or 21 hours’ drive north of Vancouver in an area known for the largest natural hot springs in Canada.

Highway serial killer

Some media reports raise the prospect of a serial killer linked to the Highway of Tears murders, but the freeway where more than 40 people have been murdered or went missing is located 1000km south of where Mr Fowler and Ms Deese were killed.

The RCMP also distanced itself from the serial killer theory.

“I don’t think it’s a serial killer,” Ms Deese’s father, Dwayne, told the Observer.

“I think of someone who has been convicted of violent crimes before, someone on drugs.

“What worries us is that person is still on the loose and they have a head start. This is going to happen again.”

“They were deeply in love,” British Deese said. “They met traveling and that’s just what they did – travel. He was working in Canada and they were planning an extensive road trip there for three weeks. They were going to spend a week on the ranch and the second half of the trip going to national parks in Canada.”

The RCMP released photos of Mr Fowler, Ms Deese and their Chevrolet van on Friday, also issuing a plea for witnesses who were on the freeway between 4pm on Sunday July 14, and 8am on Monday July 15.

They are particularly interested in anyone with dashboard cameras.

-with AAP