Footage has been released of an Australian man and his American girlfriend hugging at a petrol station the day before they were shot dead in Canada.

Lucas Fowler, 23, and Chynna Deese, 24, were found dead on the Alaska Highway in British Columbia on Monday 15 July.

Two days before, at around 7.30pm, the young travellers filled up their blue van at a petrol station in Fort Nelson and were filmed on CCTV embracing.

The heartbreaking video shows Ms Deese cleaning the van's windows while Mr Fowler filled up the tank.

Ms Deese put the window cleaner down and perched by the pumps before her boyfriend tickled her belly and wrapped his arms around her.

The couple then went inside to pay, got back into their van and continued their trip of a lifetime.

But at some point between Sunday afternoon and Monday morning, the couple were brutally murdered at the side of the road.

Police investigating the double homicide on Monday released a sketch of a bearded man who was seen talking to the couple on the highway.

Trip of a lifetime: On Saturday night, at around 7.30pm, the pair filled up their blue van at a petrol station and were seen embracing on CCTV footage

Working together: The heartbreaking video shows Ms Deese cleaning the van's windows while Mr Fowler fills up the tank

Canadian authorities released a sketch of a bearded man (pictured) who was seen talking to the couple on the highway

Tragic: Chynna Deese, 24, of Charlotte, North Carolina and her boyfriend, Lucas Fowler, 23, of Sydney, were shot dead on the side of a road in rural British Columbia

The Royal Canadian Mounted Police said the man was driving a Jeep Cherokee with a black stripe on the bonnet.

A passerby saw Mr Fowler talking to the bearded man who police want to speak to but say is not a suspect.

Road worker Alandra Hull told the Nine Network she saw Mr Fowler and Ms Deese on the highway the night before they were found dead talking to a bearded man who 'kind of looked frustrated or something'.

Five days after the couple was found dead, police found a body near a burning pickup truck about 470km away

On Monday officers said it is possible the death was linked - and were barraged with questions by journalists.

'Why can't you give us an indication of how he died?' one reporter asked.

'The public is wondering what is going on. They're not getting answers from you. Why can't you give us an idea about whether there is a linkage? Is there a serial killer? People have the right to know.'

Despite the questioning, police refused to say if the third man found dead was murdered.

'It's unusual to have two major investigations of this nature going on at the same time in northern British Columbia so we recognize the possibility that these could be linked,' a police spokesman said at a press conference.

Two teenagers who were driving the pickup truck, 19-year-old Kam McLeod and 18-year-old Bryer Schmegelsky, are missing.

The disappearance of the two men comes a week after New South Wales man Lucas Fowler, 24, and Chynna Deese, 23, from North Carolina, were shot dead on the province's remote Alaska Highway

This Chevrolet mini-van was found at the scene (pictured). The pair were only two days into their ten day journey when they were killed after their van reportedly broke down

Missing: Kam McLeod and Bryer Schmegelsky have disappeared driving around the same region of Canada as Australian man Lucas Fowler and American woman Chynna Deese

This is the red and grey Dodge 'pickup truck' that Kam McLeod and Bryer Schmegelsky were travelling in when they disappeared

Sgt Shoihet said investigators were not treating the teens as suspects but wanted them to contact authorities.

'We're hopeful they're alive,' Sgt Shoihet said.

Police also released a sketch of the man who was found dead near the burning pickup.

They ruled out the man being one of the teenagers.

They described him as being white and aged 50 to 60-years-old.

Mr Fowler's father Stephen, a senior NSW Police officer, addressed media at a press conference on Monday.

'It's the worst love story ever': Lucas Fowler's father breaks down as he talks about the double murder Mr Fowler's father Stephen, a senior NSW Police officer, addressed media at a press conference in Canada on Monday. He said the pair were beautiful and loved each other and their deaths had torn two families apart. Talking about his son's trip, he said: 'He came to Canada and he planned a trip in a van with Chynna. 'It's a love story that's ended tragically. It's the worst ever love story. 'We have two young people who had everything ahead of them who have been murdered.' 'I may be an experienced police officer, but today I'm standing here as the father of a murder victim,' Fowler said. 'Nothing prepares my family for what we are going through now.' 'We're just distraught'. Mr Fowler's father Stephen (pictured), a senior NSW Police officer, addressed media at a press conference in Canada on Monday Advertisement

'I may be an experienced police officer but I'm standing here as the father of the murder victim,' Chief inspector Fowler, of Sydney's northwest Hills district, told reporters.

'We're just distraught.'

On Monday Ms Deese's family said they are 'never going to get full closure' following the deaths of the pair who met in Croatia in 2017.

Speaking to Good Morning America Chynna's brother British said: 'It doesn't add up and it's concerning and we are never going to get full closure on this and its going to hurt the rest of our lives.'

Chynna's mother Sheila Deese said their story is like a love story that you would read about.

'This Southern girl meets this wonderful Australian man. They were just so in love and both loved traveling.

At some point between Sunday afternoon and Monday morning, the couple (pictured) were brutally murdered at the side of the road

Sheila and British Deese, left and right, have paid tribute to tragic Chynna after she was found murdered on Canadian highway with her Australian boyfriend Lucas Fowler

'As a mom, this is so hard because she was part of me. Kind of my mini me.

'The hardest part for me is to watch my other children hurting and suffering and their memories. They say you're only as happy as your saddest child I'm missing one child and I have three very sad children.'

The pair were only two days into their ten-day journey around the northwest of the country when they were killed after their van reportedly broke down.

Road worker Alandra Hull told Nine News she saw the couple 'in a heated exchange with a bearded man'.

She said the couple seemed bothered by the exchange and the man had approached them from his grey car.

Another road worker and medic named Trevor, who found the couple after they had been shot, said the back right window of the couple's van was smashed.

Road worker Alandra Hull said she saw the couple 'in a heated exchange with a bearded man'

The couple met in 2017 and spent the next two years sharing their love of travel by visiting Central and South America, Japan and South East Asia

The couple were travelling in the upper region of British Columbia, a place notorious for 'The Highway of Tears' - a 720km stretch of road upon which 50 women have disappeared or been murdered since 1970.

A couple who drove by offering help said Fowler told them they did not need help with their broken-down van.

The passerby said: 'The gentleman insisted that they were okay and that he didn't need our help and that in that same day somebody so evil would do something so horrific to them, that's just terrible.'

Mr Fowler, from north-west Sydney, dropped out of school in year 10 to become an apprentice mechanic before he left Australia to travel the world.

He met Ms Deese, from Charlotte, North Carolina, in 2017 and they spent the next two years visiting Central and South America, Japan and South East Asia.

Ms Deese recently completed a bachelor's degree in psychology and business at Appalachian State University, according to her Couchsurfing page.

In the profile she wrote that her mission was 'traveling the world and looking to meet new people and experience new places from a local's point of view'.

Ms Deese, who was learning Spanish and studied winemaking in France, described herself as 'easy going' and 'open minded with a positive attitude'.

She was reportedly working as a bartender in her hometown before she commenced her travels with her boyfriend.