BILLINGS, Mont. (AP) — Authorities are trying to determine if a body found in western North Dakota is that of a Montana high school math teacher.

Forty-three-year-old Sherry Arnold disappeared Jan. 7 during a morning run near her Sidney, Mont., home, about 50 miles from Williston, N.D., where the body was found.

Authorities say they started recovery efforts Tuesday and found the body Wednesday, and it had been buried. It's still not clear what led them to that location.

Twenty-two-year-old Michael Keith Spell and 47-year-old Lester Van Waters Jr., both of Parachute, Colo., pleaded not guilty last month to one count each of aggravated kidnapping.

They could face the death penalty if convicted. And the location of the body across the state line from where the kidnapping occurred means there could be federal charges.