Jan. 11, 2012 -- Police and now the FBI are racing against the clock to find clues leading to a missing Montana teacher but will scale back searches in her hometown that began when the 43-year-old mother of two vanished four days ago.
Sherry Arnold disappeared seemingly into thin air near her Sidney, Mont., home after she went for a jog Saturday morning, leaving authorities to find the beloved math teacher.
Investigators interviewed a local resident Tuesday who believed he was the last to see Arnold when she jogged past his car at about 6:30 a.m. Saturday.
"I'm not 100 percent sure, but I have a strong feeling it might have been [Arnold]," local resident Lonnie Lyttle told ABC News.
Investigators searching for Arnold are becoming desperate for a break and say they don't have much to go on, but police told ABC News that they will reduce their search today, calling off the sizeable search parties that have involved more than 1,000 members of the community in the past few days.
Some are now concerned that the popular teacher who has worked in Sidney since 1993 could have been abducted and taken across the nearby Canadian border. Others, such as Sidney Police Chief Frank Difonzo, believe she will be found.
"I'm going to be optimistic that we are going to find Sherry. I want us to find Sherry," Difonzo said.
Since she disappeared Saturday, so many volunteers showed up to help in the search that school busses were needed to move them. Searchers scoured countless square miles of terrain, but they've found only one clue so far: one of her running shoes.
Hundreds of Arnold's friends and neighbors packed a family church to pray overnight, and husband Gary Arnold has said that while the turnout for his wife has brought tears to his eyes, it has felt like an eternity since she went missing Saturday.
"It's horrible," he said. "It's a nightmare, but it's what you go through to get somebody back you love, I suppose."
The couple have five children between them from previous marriages. Gary Arnold has three and she has two.
Sherry Arnold, who grew up in Sidney, is a cancer survivor and Scrabble lover, who just last week traded the board game to take up "Words with Friends" online. Her kids, Jason and Holly, say she's the math teacher all the kids hope they get.
"Everybody loves her at school. Everybody just loves her. If you met her you'd love her," son Jason Papineau told ABC News, while her daughter, Holly Papineau, added that fellow students tell her that her mom is their favorite teacher.
While the FBI is now in Sidney helping local police, if she were kidnapped and taken across the Canadian border -- which is about 100 miles north – her disappearance would then become a federal case.
Arnold has brown eyes and black hair. She is 5 feet, 10 inches tall with a slender build, weighing about 140 pounds. She was last seen wearing a hooded sweatshirt with white stripes on the sleeves, red nylon pants with black leggings and black gloves.
Authorities are asking that anyone with information regarding Arnold's whereabouts please call the Sidney Police Department at 406-433-2210.