Two NSW homicide detectives will act as family liaisons after the son of one of the state’s top officers and his girlfriend were found dead along a Canadian highway.

They confirmed on Saturday that Fowler and his American girlfriend, Chynna Noelle Deese, were shot dead on Monday on the Alaska highway, 20km south of Liard Hot Springs, British Columbia.

The pair met at a hostel in Croatia two years ago, fell in love and on their latest globetrotting escapade packed up an old blue van and set off for a road trip across Canada.

Their bodies were found in a secluded area almost 1,900km, or 21 hours’ drive, north of Vancouver, the Royal Canadian Mounted Police (RCMP) said.

It’s known for the largest natural hot springs in Canada, in a region subject to subzero temperatures.

“Maybe the van over heated or broke down,” Chynna Deese’s heartbroken brother, British Deese, told the Charlotte Observer newspaper.

“Something happened on that road, some sort of conflict.”

Some media reports raised 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 1,000km south of where Fowler and Deese were killed, and Canadian authorities said there was no evidence a serial killer was responsible.

NSW Police assistant commissioner Mark Jones told reporters in Sydney on Saturday that two homicide detectives would act in a liaison-type role.

“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.”

Fowler’s father, Stephen, chief inspector for Sydney’s north-west Hills district, and other family members have flown to Canada “to be with our boy and to bring him home”.

“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.

One of the last people to speak to Fowler and Deese appears to be Sandra and Curtis Broughton, a Canadian couple who said they were driving past, saw the broken down blue van and stopped to help. Curtis is a mechanic.

“This makes my heart so sad,” Sandra Broughton wrote on Facebook. “I can’t believe that this young couple are dead now.”

Deese’s father, Dwayne, told the Observer: “What worries us is that person is still on the loose and they have a head start. This is going to happen again.

“There needs to be some kind of a warning system in place for tourists.”

The RCMP released photos of Fowler and Deese on Friday, and issued a request for witnesses and video from motorists who may have had dashboard cameras.

“Police would like to speak to anyone that may have travelled this stretch of highway between Sunday, July 14, 2019 at 4.00pm and Monday, July 15, 2019 at 8.00am,” the RCMP said in a release.

“Police would especially like to speak with anyone who may have a dashcam video while travelling that area.”

• This story was amended on 22 July 2019 to correct an earlier report that the NSW detectives would actively assist the RCMP in its investigation.