Sherry Arnold , a 44-year - old math teacher from Sidney , Montana , was on a morning jog on January 7 , 2007 , when she was abducted . Michael Keith Spell , 25 , of parachute , Colorado , confessed at the time to pulling her into a car while his friend , Lester Van Walters Jr , strangled her . Arnold was then buried 50 miles away near Williston , North Dakota . Defense experts said Spell did not understand the charges against and was mentally unfit to walk trail . prosecutors agreed he was mentally ill but said he should stand trial , facing 10 years prison .
Sherry Arnold , a 44-year-old math teacher from Sidney , Montana , was on a morning jog on January 7 , 2012 , when she was abducted . Michael Keith Spell , 25 , of parachute , Colorado , confessed at the time to pulling her into a car while his friend , Lester Van Walters Jr , strangled her . Arnold was then buried 50 miles away near Williston , North Dakota . Defense experts said Spell did not understand the case against and was mentally unfit to stand trail . Prosecutors agreed he was mentally ill but said he could stand trial , recommending 100 years prison .