Human remains recovered in North Dakota on Wednesday were believed to be those of a well-respected Montana high school math teacher who vanished in January while jogging near her home in a fast-growing agricultural community, the FBI said.
Sherry Arnold, 43, was last seen setting off for a morning run on January 7 in her hometown of Sidney in northeastern Montana. Her husband reported her missing when she did not return home.
Two Colorado men, 47-year-old Lester Vann Waters and Michael Keith Spell, 22, were arrested the following week in connection with Arnold's disappearance and charged with aggravated kidnapping.
Authorities said at the time they believed the Sidney High School math teacher was dead, but her body remained missing.
"While positive identification has not been made at this time, it is believed the remains are those of Sherry Arnold of Sidney, Montana," the FBI said in a statement issued with the Sidney Police Department.
The remains were found in the vicinity of Williston, North Dakota, about 40 miles from Sidney, the FBI said. It said no additional details would be released pending positive identification.
In a sworn statement made public in February, Montana's Richland County prosecutor Mike Weber said Spell had confessed to a role in Arnold's kidnapping and murder.
According to the 12-page affidavit, posted online by the Sidney Herald newspaper, Spell told authorities that Waters, in a crack-induced frenzy, ordered him to grab Arnold and pull her into the Ford Explorer they were riding in.
Spell told authorities that Waters then got into the back seat with Arnold and "choked her out," according to Weber's sworn account. Weber said that, according to Spell, the pair then drove to Williston, bought a shovel and buried Arnold in a shallow grave.
Spell said he later felt remorse when he saw posters of the missing teacher, telephoned his family in Colorado and told them what had happened, then hitchhiked to Rapid City, South Dakota, the affidavit said.
Authorities identified Waters and Spell as suspects after a tipster called a police hotline to say that Spell's girlfriend said he had told her that he and Waters "picked up a lady walking along the road, killed her, and then buried her," according to the affidavit.
The disappearance of Arnold, who colleagues described as a well-respected and well-liked teacher, cast a pall over Sidney, a 5,000-population farming community coping with an influx of newcomers linked to energy production.
(Reporting by Dan Whitcomb; Editing by Greg McCune and Cynthia Johnston)