Police have found a new lead in the case of Matthew Greene, a popular math teacher at Nazareth Area High School, who disappeared over a month ago while on a hiking trip in the California mountains.

According to USA Today, Greene was last heard from on July 16, when he was awaiting repairs for car trouble at a campground in Mammoth Lakes, California. He was meeting friends on the trip, but told them to continue while he waited at the campground.

Greene was hiking the Eastern Sierra Mountains, but his loved ones say he is a very experienced and smart hiker and it is not like him to take risks while in the wilderness.

After searching the area and the wilderness and investigating any leads, police started to assume some sort of accident happened to him. On Friday, a hiker found a pair of glasses hanging from a sign on one of the trailheads that looked extremely similar to ones that Greene wore.

His family now fears foul play and will continue their search efforts.

"We kind of have realistic expectations," said his sister, Tiffany Minto, Huffington Post reports. "We may never get answers as to the how and the what. But we will settle for anything we can get to just bring him home and get some closure on it."