Two men suspected in three B.C. killings have nothing to lose and the danger of more violence increases as police in northern Manitoba intensify their search, criminal psychologists warn.

"There's no turning back now," said Eric Hickey, a Canadian criminal psychologist now living in California, and a faculty member in the department of forensic psychology at Walden University.

A massive ground search for Kam McLeod, 19, and Bryer Schmegelsky, 18, is still underway near Gillam, Man., and Fox Lake Cree Nation, RCMP said Friday.

The Port Alberni, B.C., men are suspects in the shooting deaths of a tourist couple in northern B.C. last week, and have been charged with second-degree murder after a man's body was found days later near Dease Lake.

On Monday, a burnt-out vehicle that had been driven by the suspects was found near Fox Lake, and the men are believed to have fled into the bush. On Thursday, RCMP announced there had been two confirmed sightings of the men in the area before that vehicle was discovered.

They also said there have been no reports of other stolen vehicles, which leads them to believe they are still in the area.

"I suspect they're in hiding for a short time until they run out of resources," said Hickey. "They're going to go on and run again and when they do, of course, they are very dangerous."

A vehicle driven by Kam McLeod and Bryer Schmegelsky, wanted in connection with three B.C. homicides, was found burned outside Gillam, Man. on Monday. (Billy Beardy)

Harsh environment

The swampy, buggy terrain has few paths and would make it difficult to escape, people with knowledge of the area have told CBC News.

"Who knows what kind of gear they have. It would be very challenging and they're running on fear and adrenalin," Sherry Benson-Podolchuk, a former RCMP officer, told Ismaila Alfa, host of CBC Manitoba's afternoon radio show Up to Speed.

That fear will likely increase as McLeod and Schmegelsky begin to "feel the world closing in," said Jooyoung Lee, an associate professor in the department of sociology at the University of Toronto, and an expert in criminal psychology.

"The most mundane things become fraught with anxiety because you are now a wanted person, and you are now visible on TV and various media across the country or province," Lee said.

People are locking their doors, night and day. - Karen Donnellan-Fisher, resident

Gillam, about 740 kilometres north of Winnipeg, is one of the northernmost Manitoba communities accessible by road year round. RCMP have set up a checkstop at the intersection of highways 280, which is the only road in and out of Gillam, and 290, which goes north and is the only road to Fox Lake.

As the search continued Friday morning, the weather turned cold and sometimes rainy.

Police dogs, a drone and heavily armed officers are combing the area. A helicopter has also been brought in to help with the search.

The manager of the town's only gas station, convenience store and liquor store said people in the community want the search to end as soon as possible, but for the most part locals have been trying to go about their business .

"The only difference is people are locking their doors, night and day," said Karen Donnellan-Fisher.

'Act of retribution'

McLeod and Schmegelsky are suspects in the double homicide of Australian Lucas Fowler, 23, and American Chynna Deese, 24, who were discovered shot to death along the side of the Alaska Highway south of Liard Hot Springs, B.C., on July 15.

They are also charged with second-degree murder in the case of Leonard Dyck, a sessional instructor at the University of British Columbia.

Lee, who has studied mass killers, said killing sprees often begin as a "fun, adventurous prelude before either a suicide pact or a shootout with law enforcement.

Images of murder suspects McLeod and Schmegelsky recorded in northern Saskatchewan a few days after three people were found dead in B.C. (RCMP)

"This killing spree is conceptualized as a final act of retribution against a world that you believe has wronged you in some way."

Usually when two or more people go on a killing spree together, one tends to be the leader, the psychologists said. Hickey expects McLeod and Schmegelsky to stay together, at least as long as they are in the bush and dependent on each other for survival.

When people are on the run, however, the stress can cause those bonds to fray, Lee said.

"You can see instances where the person who is going along with it suddenly feels way in over their head and realizes that they didn't sign up for this," he said. "And that's the best opportunity, in a way, for this to end peacefully without any more bloodshed."

Hickey suspects both men had troubled childhoods, which feeds into their violent behaviour.

"These kids probably didn't come from happy homes and it doesn't give them the right to act out … but these things didn't happen all at once.

'Fight or flight'

In an interview with The Canadian Press, Schmegelsky's father, Alan, said his son had a troubled upbringing. He struggled through his parents' acrimonious split in 2005, and his main influences became video games and YouTube.

As they get closer to catching the two men, police themselves may begin to feel the stress of a looming potential showdown.

"Police officers are well aware that when people are on the run and when they have this fight or flight mindset, the potential for retaliatory violence is extraordinarily high," Lee said.

The RCMP issued a public alert for Schmegelsky and McLeod on July 23. (Ben Nelms/CBC)

When Schmegelsky was still considered missing, his father told CHEK News the men considered themselves survivalists.

Police should not underestimate the ability of the two men to last in the wilderness, Hickey said.

"If they know how to fish, or anything like that, they'll do what they have to do to survive."

Police have warned anyone who sees the two young men not to approach, as they are considered armed and dangerous.

"If they come across a cabin, or a fisherman, or ... a hunter, they would be in serious trouble," Hickey said. "They have nothing to lose at all."