Sixteen days after two teens began leaving bodies by the Alaska Highway, more witnesses are coming forward with chilling and detailed accounts of how they encountered the killers and watched them drive away.

Yesterday it was revealed Bryer Schmegelsky, 18, and Kam McLeod, 19, were stopped and checked for alcohol before being allowed to continue their escape across rural Canada.

Today, another local has come forward with the story about how he came across the country's most wanted men and didn't realise until it was too late.

Tommy Ste-Croix said not only did he talk with Schmegelsky and McLeod, but he also helped them get their bogged Rav-4 back on the road.

Mr Ste-Croix was visiting his brother in Cold Lake, Alberta, on July 21 when the family noticed a vehicle had become stuck in mud.

It was about 11am and the pair were travelling east from British Columbia where the bodies of Australian man Lucas Fowler, his American girlfriend Chynna Deese and BC sessional lecturer Leonard Dyck were found by the side of the highway. All three had been murdered.

Mr Ste-Croix wrote on Facebook about the bizarre encounter — an encounter that he said left him feeling "something wasn't right".

"Holy f***, my big heart could of (sic) got me killed," he wrote. "One shot to the back and that would of been it."

Mr Ste-Croix said he approached the car in an alley next to a football field and chatted casually with them. They told him their real names, joked with him and shook his hand.

"I pulled these guys out Sunday around 11 am, they still appear the same as in the pictures (from CCTV shared by police).

"Same shaggy beard, tall skinny fella was wearing a white shirt with camo army pants I believe ... same hair cuts everything.

"They got stuck behind Cold Lake Hospital in a grey Rav-4. 2015-ish I'd have to say.

"Wish I'd of known, something wasn't right with these guys. Even shook their hands after getting them unstuck. Blows my mind, guess I look like a mean motherf***er cause they were two and could of got my truck to take off with especially for being murder suspects.

Mr Ste-Croix told CBC News he joked with them that their parents would be mad if they knew the predicament they were in.

"Mom and dad's going to be pissed," he told them before one of the teens joked back.

"They looked at me and said, 'No, mom and dad told me to go for a long joy ride'," Mr Ste-Croix said.

He said the two teens shook his hand and did not make up fake names when he asked who they were. But he could tell something wasn't quite right.

"You could tell they were nervous," Mr Ste-Croix said.

Two days later the same teens were front page news. They were officially suspects in three murders.

The sighting helps join the dots along the highways connecting British Columbia with Alberta, Saskachewan and Manitoba — where the teens were last spotted.

It follows a remarkable account from First Nations police who said they stopped the teens in Split Lake, more than 1200km east of Cold Lake, on July 22.

Rookie Band constable Albert Saunders — whose job it is to enforce specific provincial bylaws — pulled them over and checked if they were carrying alcohol after they drove through a checkstop. Split Lake is a dry community.

"I told them that you know you're supposed to stop ... and then they said sorry about that, the driver said sorry, and then I asked them where they came from and they said Vancouver," the Band constable from the Tataskweyak Cree Nation told CBC News.

"They kept saying, 'Sorry, sorry'," he said.

He said the teens seemed "paranoid" when talking to officers.

The sighting is supported by previous reports that Schmegelsky and McLeod stopped for petrol in Split Lake where the question about alcohol was raised.

Last week, service station attendant Mychelle Keeper said McLeod paid for $20 worth of petrol but Schmegelsky asked casually whether he could consume alcohol in the dry community.

"The guy who paid for the gas — he was quiet, he didn't say anything, he was just looking down," she said.

"They seemed like, I don't know, normal. I'm just so nervous right now thinking about it."

The teens were named as suspects the following day.

The manhunt for the pair has been scaled back in the remote river town of York Landing after two men matching their description were spotted rummaging through landfill.

York Landing is 90km from Gillam, where the Rav-4 they were driving was torched and where authorities have focused their search.

Royal Canadian Mounted Police said they were "unable to substantiate the tip".

"The heavy police presence in York Landing has been withdrawn and policing resources in the community will return to normal. The RCMP thanks the community for their patience and understanding," police said in a statement today.

The York Landing tip included information the two people sighted were wearing the same clothing — Schmegelsky in a camouflage jacket and McLeod in a blue T-shirt — they were pictured in on CCTV footage from a hardware store in Meadow Lake, Saskatchewan.

Dave Arama is one of Canada's leading survival experts.

He knows the dangers lurking in the swampy sub-Arctic boreal forest around Gillam, Manitoba, where the accused teen killers are suspected of hiding out for a week.

If the duo did enter the wilderness and did not find some type of shelter, Mr Arama predicts they are dead or close to it.

It is not the black bears, polar bears or wolves Mr Arama places high on his top 10 list of dangers the teenagers would face.

It's the insects.

There's relentless blood-sucking deer flies, mosquitos, sand flies and other bugs.

"They eat you alive," Mr Arama, owner of the Ontario-based WSC Survival School, told AAP on Tuesday.

"They won't stop biting until until your eyes close and you can't see no more.

"Or, if you get enough bites you can go anaphylaxis and then end up in a serious life-threatening reaction."

Water might be plentiful in northern Canada during summer but instead of keeping the teenagers alive it also could be highly-hazardous.

"If they drink any water it is likely filled with parasites,giardia and they'd get sick as hell from that," he said.

"I'll be honest. With 40 years of experience, if you threw me out there with no knife, no tin can, no flint to start a fire, no tarp, no nothing, I'd rather die.

"This is no Crocodile Dundee movie. This is real."

Mr Fowler, from Sydney, and Ms Deese, from Charlotte in North Carolina, had been travelling through northern British Columbia en route to Alaska when they were found next to their blue Chevrolet van on July 15.

On July 19, Mr Dyck, a University of British Columbia lecturer, was found dead near Lake Dease, two kilometres from the teens' burnt-out Dodge and almost 500km from where Mr Fowler and Ms Deese's bodies were discovered.