(AP) -- New details about the mysterious disappearance and reported death of a small-town Montana math teacher began to trickle out Sunday, as authorities asked property owners in parts of North Dakota and Montana to look for signs of her buried body, and released the names of two men being held in the case.
The FBI issued a statement late Sunday saying the body of 43-year-old Sherry Arnold of Sidney, Mont., might be buried in a "shelter belt," or a line of trees that protects soil from the wind. The agency asked that property owners in three North Dakota counties -- Williams, McKenzie and Mountrail counties -- and in far northeastern Montana check vacant farmsteads for signs of disturbed soil or matted grass.
"Based on investigative evidence gathered over the last few days, it is believed that Ms. Arnold may be deceased," FBI spokeswoman Debbie Bertram said in a statement. "Her body has not been recovered."
Authorities said 47-year-old Lester Vann Waters Jr. and 22-year-old Michael Keith Spell, both of Parachute, Colo., were in the Williams County Correctional Center in Williston, N.D., awaiting extradition to Montana.
Williams County Sheriff's Deputy Jon Garrison said the two men face aggravated kidnapping charges in Montana.
The FBI said in its statement it is asking only for the help of landowners in the three North Dakota counties and in extreme northeast Montana, and it is not seeking other volunteers for a search. The agency said property owners who discover something unusual should not disturb the area, but call authorities.
Officials said Waters and Spell were brought to the Williston jail Friday. They declined to release where or how the men were taken into custody.
The jail is about 46 miles from Sidney, where officials say Arnold disappeared while on an early-morning run along a truck route on the edge of the oil boom town of about 5,500 residents.
"Well, obviously, it's not over," Sidney Mayor Bret Smelser said when told of the FBI news release. "We're angry. We're frustrated. But our concern is with Sherry's family and friends. And whatever support we can give to get them through this, that's what we'll do."
Sidney school officials posted a statement online Friday saying they learned of Arnold's death that day. The statement provided no details.
In the days after Arnold disappeared, hundreds of residents, police, firefighters and others combed the town and surrounding countryside without success.
The only clue that has been publicly released was that one of Arnold's shoes was found along her running route.
Arnold and her husband, Gary Arnold, have five children combined from prior marriages. Two live at home and attend the same school system where Sherry Arnold worked for the past 18 years.