A burnt-out camper van belonging to the lifelong friends - Kam McLeod, 19, and Bryer Schmegelsky, 18 - was discovered on Friday along the highway in northern British Columbia.
Days before, two tourists were found shot to death 500km (310 miles) away.
Police say Mr McLeod and Mr Schmegelsky have since been spotted driving out of the province and are now suspects.
They were previously described by police as missing, with the implication that they may also be victims of the killer.
A third unidentified body was found near the young men's burnt out van.