Canadian authorities are trying to solve what has turned into an international murder mystery — the brutal killing of an American woman and an Australian man.

The young couple, who had been touring British Columbia, were found shot dead on the side of a remote highway on Monday.

Grieving family members have said that they are getting little information from Canadian authorities — but that they’ve been led to believe the deaths were “brutal.”

“What worries us is that person is still on the loose and they have a head start,” the brother of victim Chynna Noelle Deese told the Charlotte Observer.

Deese, 24, was from Charlotte, and her boyfriend of two years, Lucas Robertson Fowler, was the son of a police inspector in the southern Australian state of New South Wales.

“They were deeply in love,” the woman’s brother, British Deese, told The Observer.

“They met traveling and that’s just what they did – travel,” the brother told the paper.

“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 [a cattle ranch] and the second half of the trip going to national parks in Canada.”

The two had only been traveling for a few days when they were found — and it took authorities three days to identify the bodies, suggesting that their IDs were taken.

The two were veteran travelers, adding to the mystery, the brother said. They had met at a hostel in Croatia in 2017, and since then had traveled extensively throughout Europe, Central America and Asia.

The brother also said that Canadian authorities have told the family that an open casket would be out of the question — leading family members to conclude that the murders had been “brutal.”

“They were bright souls,” another of Deese’s brothers, Kennedy Deese, posted on Facebook earlier this week. “We are all still in shock and heartbroken.”

The Royal Canadian Mounted Police were investigating, and have asked anyone with information about the double homicide to contact them.