Third body found on Highway 37, the same week Lucas Fowler and Chynna Deese were killed

Lucas Fowler, of Australia, and his American girlfriend Chynna Deese have died in suspicious circumstances on a remote highway in Canada. Photo / Facebook

A third body has been found on a Canadian highway but while authorities are "looking at all of the leads", they are not linking the death to the mysterious shooting murders of Australian tourist Lucas Fowler and his American girlfriend Chynna Deese.

The body of a man was found on Friday near a burning pick-up truck south of the Stikine River Bridge on Highway 37 in northern British Columbia.

Mr Fowler, 23, from Sydney, and Ms Deese, 24, from North Carolina, were found dead on Monday about 750km away on the side of the Alaska Highway after their blue 1986 Chevrolet van broke down.

Lucas Fowler and girlfriend Chynna Deese. Photo / Facebook

"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 yesterday.

"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."

Lucas Fowler, of Australia, and his American girlfriend Chynna Deese have died in suspicious circumstances on a remote highway in Canada. Photo / Facebook

The discovery of a man's body on Friday came after police responded to a report of a pick-up truck on fire south of the Stikine River Bridge. There was no one in the vehicle.

A passing motorist later told the officers they had observed what appeared to be a body at a nearby highway pull-out area.

When the officers investigated, they found the man's body.

Canadian mounted police have released few details about the Stikine River Bridge death and the shooting deaths of Mr Fowler and Ms Deese.

They have hosed down speculation a serial killer might be the perpetrator.

Images of the van released by police. Photo / Supplied

Mr Fowler and Ms Deese were on a Canadian road trip last Sunday on the Alaska Highway, 20km south of Liard Hot Springs, when their old van broke down.

Passing motorists saw them, including Canadian couple Curtis and Sandra Broughton who stopped to offer assistance just before 3.30pm on Sunday.

Mr Broughton, a mechanic, said he spoke to Mr Fowler but the young Australian seemed to know how to fix the van.

"The vehicle was flooded out and they were going to try and get it going again until they could get the parts they needed," Mr Broughton told AAP.

The Broughtons got back in their car and drove home.

Mr Fowler and Ms Deese were found dead the next day.

Chynna Deese had been on a road trip with her Australian boyfriend when they were killed. Photo / Facebook

The Royal Canadian Mounted Police are leading the hunt for the killer and believe the killings happened between last Sunday and Monday.

Police investigators want to speak with anyone who may have been travelling near Liard Hot Springs on Alaska Highway 97 between 4pm Sunday and 8am Monday.

They are particularly interested in motorists with dashboard cameras who may have been filming.

Police would also like to speak to anyone who was staying at camping sites in the area.

Mr Fowler is the son of one of NSW's most senior police officers, Stephen Fowler, the chief inspector of Sydney's northwest Hills district.

The Fowlers are making the long, heartbreaking journey from Sydney to British Columbia "to be with our boy and to bring him home".

Two NSW homicide detectives also travelled to Canada to help as liaisons.

Lucas Fowler in a post shared by his family on Facebook. Photo / Facebook

The injuries inflicted were so "brutal", Ms Deese's heartbroken brother said the family was told an open casket would not be allowed at her funeral.

"To lose someone so young and vibrant, who was travelling the world and just enjoying life to the full, is devastating," the Fowlers said in a statement.

Ms Deese's mother Sheila Deese told Canadian news station Channel 9 her daughter "loved people" and "was cautious".

"It's tragic when someone dies, but when they're in another country, you can't go and be near them," Sheila Deese said.

"You can't be face-to-face and ask questions or go and see where it happened. I don't want it to happen to someone else. I do want to find the person who did it."