With no new developments in their hunt, police are scaling back the search for a Whitby, Ont. man who was reported missing on Monday morning.

Durham Regional Police have searched a 15- to 20-kilometre radius around Boucher's home, and have found no evidence of 52-year-old Jeffrey Boucher's whereabouts or wellbeing.

Starting Thursday night and continuing into Friday, resources will be scaled back, but Sgt. Nancy Van Rooy said "we will continue our search, ground and air."

Though the number of people involved in the search will decrease, police are expanding the geography of their search in all directions, hoping there's an area they've missed.

"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," Van Rooy said in a news conference on Thursday morning.

Police are considering a number of theories, but they say there is no evidence to suggest foul play Boucher's disappearance.

Proceeding on information that Boucher went for a routine morning run on Monday, police have been concentrating their search on ravines, ditches and wooded trails within the area surrounding Boucher's home near Tauton Road and Brock Street.

The roads and trails were icy the morning Boucher was reported missing, and it is thought that he may have slipped and become incapacitated.

Although no one witnessed Boucher leave the house Monday morning, relatives and friends have said he likely left for his daily run at approximately 6 a.m. as he usually does. Boucher liked to run alone, and was known to frequently change his route.

After he failed to return, Boucher was reported missing at 8:30 a.m.

Experts at CFB Trenton told police if Boucher was outside in running gear, he would likely survive a "maximum of 24 hours," Van Rooy said. "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.

"We are going to keep the hope that despite the obvious mid-January winter weather, that he has gone indoors and he's going to be okay," she said. "We'd like to have closure here."

Multiple theories

Investigators are looking into a number of theories including all aspects of Boucher's life, but they said there is no evidence to suggest he didn't go for a run. Following multiple leads, police told media they're also looking into Boucher's mental health, relationships and employment, but they said Wednesday that he appears to be an outstanding and reliable citizen.

Police said they've searched his family ski cabin for signs, and they continue to monitor for any banking activity.

"We are hoping that he has perhaps walked away for his own reasons or has, for whatever reason, stepped away from his usual routines of work and family. And for that reason, if he himself is listening, or others that do know his whereabouts… everyone's concerned for him," Van Rooy said.

Questions were raised on Wednesday about whether Boucher went missing for a short period Sunday evening. But police said that, while the high school teacher was out for more than two hours on Sunday, he eventually returned home.

"In the case of Sunday evening, which was Jan. 12, he stepped out for a run and he was gone for longer than expected by his family; nonetheless he did return home. He was not reported missing to us," Van Rooy said.

Kawartha Pine Ridge School Board clarified reports surrounding a large sum of money found in Boucher's desk at school last week, saying the cash was for a ski trip.

The board's director of education Rusty Hick told CP24 the $3,500 found in Boucher's desk was meant for a ski trip. Boucher ran multiple clubs at school, Hick said Wednesday, explaining that the money in his desk was therefore not unusual. Police said that the money appears to have no relevance to his disappearance.

Boucher does not own a cellphone, police added, so there is no "electronic footprint from Mr. Boucher that might indicate that there is any sort of activity at the hands of Mr. Boucher."

"It's just so confusing," Boucher's wife Kristen told CTV Toronto on Tuesday. "Honestly the only safe place to run is on the road. And if he'd been on the road, someone would have found him by now."

The working theory is that the jogger may have slipped on the ice and fell into a ditch, or was hit by a car, police have said.

Boucher's mother, Mary, said she's hopeful her son will come home.

"It's a mystery why they can't find him. My hope is he's gone somewhere, he's never done it before, and that he will come home," Mary told CTV Kitchener in an interview Wednesday.

The last time Mary saw her son was Sunday morning. She describes her son as very quiet, private but reliable.

"He would often run from the chalet but he always came back in about 40 minutes. He was just like clockwork, very scheduled, very dependable," she said.

She said he's "always in bed before 10 p.m., always," and that why he was gone for 2.5 hours on Sunday is a "mystery" to her.

Police had launched a full-scale search on Tuesday, which continued through Thursday using infrared sensors, canine units, helicopters and ATVs, as well as a volunteer emergency response team. Officers went door-to-door in Boucher’s neighbourhood, hoping someone saw something or captured images of the missing man via home-security video.

Police are also asking residents of Whitby to search their properties for any evidence that Boucher may have been there.

Joggers in the area ran some of Boucher's known routes on Wednesday to search for signs of the missing man.

Boucher, described as an experienced runner, normally departs for his runs at about 6 a.m. and returns home within the hour after running up to 15 kilometres. His car and wallet were still at home and he failed to show up for work at Bowmanville High School.

Boucher is described as white, six feet tall, 180 pounds with short grey and white hair. Relatives say he is likely wearing a dark running jacket and dark pants.

Anyone with information is asked to call police at 1-888-579-1520 or Crime Stoppers anonymously at 1-800-222-TIPS (8477).

With files from CP24's Cam Woolley