Investigators have released a sketch of a person of interest in the murder of an American woman and her Australian boyfriend. The young couple was wrapping up a two-week-long road trip through northern British Columbia when they were found shot to death last Monday by their broken-down van.

Authorities in British Columbia are also searching for two missing teens. While looking for them, they found a man's body on the side of the road. Police are investigating whether any of these cases are connected, as families of the young couple are grieving.

Stephen Fowler is sending a desperate plea for information surrounding the deaths of his son Lucas, and Lucas' girlfriend, North Carolina native Chynna Deese.

"Two young people, who had everything ahead of them, tragically murdered," Fowler said.

Surveillance video shows Chynna Deese and Lucas Fowler hugging at a gas station two days before their bodies were discovered. CBS News



Newly released surveillance video shows the couple hugging at a gas station two days before their bodies were discovered. Police also released a sketch of a person they say was seen talking to Fowler.

About 300 miles south in the same province several days later, police found a burning car belonging to two missing Canadian teenagers. During that investigation, the body of an older man was found a little over a mile away. Police released a sketch of the victim, asking for help identifying him.

"It's unusual to have two major investigations undergoing of this nature in Northern BC at the same time," said Janelle Shoihet of the Royal Canadian Mounted Police. "So we recognize that there is a possibility that these could be linked."

"48 Hours" has previously reported on a notorious remote stretch of road near these crimes dubbed the "Highway of Tears." In the last 40 years, at least 18 women have disappeared or been found murdered along it.

As authorities investigate whether any of these new cases might be related, the victims' friends and family want answers.

"He was such a friendly guy who was kind to people he didn't know, like it's surreal," said one of Fowler's friends.

Fowler's father is a police officer in Australia, and he has two colleagues with him in Canada. Police haven't determined the cause of death of the man found near the missing teens' car, or whether there was any connection.