The Montana math teacher who was found dead today may have been abducted and murdered by men who fled to Dakota.
The FBI have been investigating the possibility that Sherry Arnold, 43, was snatched when she disappeared last weekend and taken out of state
Police said two men in the Dakotas had been detained for questioning in connection with her death.
Mrs Arnold who has five children with her husband - two of her own, had been missing since January 7th when she left her house for a pre-dawn jog.
The only clue to her disappearance that was publicly released was that one of her shoes was found along her running route, near her home in the oil boom town of Sidney near the North Dakota border.
Sidney Public School officials posted a statement online saying they learned of Mrs Arnold's death Friday morning. No further information was available.
FBI Special Agent David J. Johnson, of Salt Lake City, said a tip from the public led to the two men.
Frank DiFonzo, Sidney Chief of Police, told old KFYR-TV: 'Dozens and dozens of tips were called into the tip line by residents of the area. Today as a result of a tip, we are able to announce that a significant breakthrough has occurred.'
Mr DiFonzo said police arrested a man, 47, in Williston and he's being held in the Williams County Jail. Police in South Dakota are also detaining a man, 22, in Rapid City for questioning.
Karen Arnold Truax of St. Paul, Minn., the daughter of Sherry Arnold's husband, Gary, told The Billings Gazette the family wants some privacy and 'time to process what has happened.'
She said: 'We appreciate everything that everyone did to help us in this search. We are so heartbroken that this is the outcome.
Only yesterday the victim's husband, Gary Arnold, told HLN's Jane Velez-Mitchell that he was hopeful that his wife would be found alive.
He said the disappearance had been 'very difficult' on the couple's children, though they had been trying to stay positive.
Mr Arnold said: 'Their mother has raised them well. They are troopers, they are hanging in there.'
Matthew Brenner, a senior at the University of Montana, grew up in Sidney and was taught by Mrs Arnold said she was a well-loved woman who was a great teacher and a fixture of the town.
He told KAJ18.com: 'It's a shock to me and a shock to them. I don't even know how to begin to try and start school again, but I can tell you this, she was one of the most respected people in that school system. It's gonna be rough.'
Donna Brown, resident of Sidney, told KFYR-TV: '[It's] very, very sad. Very upsetting.
'I`m thankful for the community and the family that they did find her. That there can be some closure.'
Sidney Public Schools said that 'additional counselors were on hand' to help students cope with the news.
Hundreds of residents, police, firefighters and others combed the town and surrounding countryside earlier this week. The school district played an active role in the search by lending buses to transport members of search teams and setting up a fund to defer expenses.
The disappearance rocked the small town of Sidney, population around 5,000, and located about 100 miles south of the Canadian border - which has been changing rapidly in recent years due to an oil boom.
Christine Mullen, 26, who joined the search effort, even though she didn't know Mrs Arnold told CNN: 'We're such a small community, and crime is absolutely unheard of. We don't lock our car doors. (We're) completely shocked.'
Debbie Dujanovic Bertram, an FBI spokeswoman, told FoxNews.com that investigators are 'looking into all angles'.
Mrs Arnold grew up on a ranch outside Sidney. Her husband also worked for the school and the couple have five children from prior marriages, including two living at home and attending the same school where their mother worked for the past 18 years.
Mr and Mrs Arnold had a mixed family that included at least two children born to her and other children from before their marriage.
Mayor Bret Smelser said the search had covered all of Sidney and surrounding areas of Richland County.
He said federal agents had met with family members, including Arnold's parents, Ron and Sherry Whited, and pledged to press hard for answers.
'The promise they made Ron and Sherry was that they wouldn't give up until they had found something or found Sherry,' Smelser said.
The Mayor, 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.
School superintendent Daniel Farr said Arnold was a mother and devoted algebra teacher who has taught in the Sidney system for 18 years.
'She's one of those teachers that every parent wants in front of their child,' said Mr Farr. 'She's there early in the mornings and she's there after school. She is just a generous and caring person.'