SIDNEY — The Sidney Police Department has called on the Federal Bureau of Investigation for assistance in its search for missing math teacher Sherry Arnold, 43.
"There is no information that it's an abduction, but obviously that is the direction we are leading into," Chief Frank DiFonzo said Monday. "We are not going to cease the search and rescue until we cover the entire county and have done what we need to do."
FBI agents were in Sidney on Monday, and DiFonzo said the department also plans to reach out to the state Division of Criminal Investigation for help.
"We are working it jointly and allocating resources," said Debbie Bertram, spokeswoman for the FBI, Salt Lake City Division.
She said the FBI has "multiple agents" in Sidney to assist local law enforcement. Should the investigation become an abduction case and investigators find that the Canadian border was crossed, it would become a federal investigation, Bertram said.
Arnold left her Sidney home at 6:30 a.m. Saturday to go for a run and has not returned.
Of the evidence brought back by search parties, only a shoe found Saturday was positively identified by the family as Arnold's.
The shoe was found east of the Sidney Sugars Inc. factory off Holly Street east of town, one of the areas where Arnold goes running. A witness reported seeing someone matching Arnold's description that morning near where the shoe was found, Assistant Police Chief Robert Burnison said.
Burnison said Monday's efforts started with searchers on the ground. Aircraft and search dogs would be called on as needed, he said.
Though days have passed, her family has not given up hope.
"This is a wonderful woman," Gary Arnold said of his wife. "We want her back, and we want her back healthy. I miss my wife."
Mayor Bret Smelser, who attends church with Arnold's parents, said she is "a daughter of the community" whose disappearance brought out the best in hundreds of residents from Sidney and surrounding towns who have participated in the search.
"It's just been grueling," said Arnold's father, Ron Whited, who runs a ranch outside of Sidney. "When you can't find someone and you do find a shoe and you know that's where she was running, something obviously wasn't right. I can tell you I would never believe I would be looking for my daughter."
Whited said the family had considered posting a reward for information in the case but was holding off for now one the advice of law enforcement.
Sherry Arnold has been with the Sidney School District since 1993, teaching at the middle school and most recently the high school level.
Superintendent Daniel Farr said Arnold teaches intermediate and advanced mathematics and that her teaching is "nothing short of phenomenal."
"She is the kind of person you want in front of your kids," Farr said. "She is at school early working with the kids and at school late working with the kids. She does what she has to do to make kids succeed."
Arnold's husband can attest that she uses the same care on their blended family of five children back home — all of whom are either in high school or have graduated.
Her positive influence inspired current and former students and staff members to join nearly 1,100 community members who showed up Sunday to continue the search for Arnold using horses, all-terrain vehicles and personal planes.
The number of volunteers climbed to 1,200 by Monday afternoon. A volunteer search team of 55 set out north, south and west of Sidney as specialized teams of between 70 and 90 people fanned out in four teams across rural land east of town toward the Yellowstone River.
The community support has been overwhelming to Arnold's family, but not surprising. Arnold's roots in Sidney reach back farther than anyone can remember — even to a great-grandfather who was the chief of police.
"She's a major part of the whole community. Everyone is going through it together," said Rhonda Whited, Arnold's sister. "The community is in pain."
Smelser said the outpouring of volunteers shows Sidney has remained a tight-knit community despite the changes brought by a massive influx of oil field workers in recent years.
"My big fear as mayor is that we'll lose our small-town charm and personality with the second wave of oil, but this is the way Sidney has always been. It's an amazing community," he said.
"What we need right now is everybody's prayers," Smelser said of Monday's search. "The window of opportunity is slipping on us."
Farr said Gary Arnold called him about his wife's disappearance by 9:30 a.m. Saturday. By noon, the school had become a meeting point for search volunteers. School officials began drafting a plan for students that afternoon.
The staff was prepared for when school resumed Monday, Farr said. Teachers with classes of kindergartners up to high school seniors were given a letter to read to their first-period classes. The rest of the hour was open for discussion.
"I wanted the first hour to be in front of their own teachers," Farr said. "They are the ones that can tell if someone is not doing well. They already have that connection with the student."
Arnold's math classes are being staffed by school counselors for now, though Farr said they probably will have a substitute in by midweek. The school has reached out to sister schools in the surrounding area who have agreed to provide support if the teachers need time away from the classroom.
Arnold's husband also works in the school district as a federal program coordinator alongside Farr as his "right hand man." He is taking time off.
In his years at the police department, DiFonzo said this is the first time he can remember investigating such a sudden disappearance.
"This is the first issue where we had someone go missing without some sort of background issue," he said. "It's just so sudden."
DiFonzo said he can feel the growing pains in Sidney — a town of about 5,000 only 10 miles from the border with North Dakota — as people pour in from out of town, chasing the money brought by the Bakken oil boom.
He's seen it before — the last time there was an oil boom in the 1980s.
"We have a lot of activity now at this part of the state," DiFonzo said. "A lot of out-of-state people are here to work, and locals don't know them or recognize them."
The influx has increased crime, and DiFonzo said officers are responding to more bar fights, domestic violence and drunken driving.
"We are just seeing the tip of the iceberg," he said.
Susan Smith moved to Sidney seven years ago from Las Vegas to escape violent crime. She was at the Richland Law and Justice Center on Monday to pick up a concealed-weapon permit in light of the disappearance.
Smith owns an oil field cleaning service and spends a lot of her time on the road alone.
"It's just been really scary on the road like that," Smith said. "I love Sidney, it's a small town where you don't lock your doors, but I am constantly going to lock them now."
Associated Press reporter Matthew Brown contributed to this report.