With no evidence and no new leads, police are beginning to scale back their search for missing teacher Jeffrey Boucher.

Boucher, who lives in Whitby and teaches in Bowmanville, was born and raised in Kitchener.

Family members believe the 52-year-old science teacher left his house early Monday morning for his typical morning run.

While the number of police officers involved in the search is decreasing, police say they’re expanding their search radius to encompass a larger area.

“The investigation itself is active, it’s ongoing, it is not coming to a halt until we find the whereabouts or have some determination to the welfare of Mr. Boucher,” Sgt. Nancy Van Rooy of Durham Regional Police said at a Thursday morning news conference.

Police say they’re considering a number of theories for Boucher’s disappearance – including the possibility he was hit by a car or slipped on ice and fell into a ditch – but have no evidence to suggest foul play.

Experts at CFB Trenton believe if something like that did occur, Boucher would be unlikely to survive more than 24 hours outdoors in running gear.

“It’s about the condition of this gentleman, it’s about his clothing, it’s about hydration, it’s about the terrain he might be in … it is just too extreme to survive,” said Van Rooy.

Family members have said Boucher left the house Sunday night – and although he did return home around 11 p.m., the entire incident is considered out of character for him.

With files from CTV Toronto