Montana prosecutors won't seek death sentence for mentally disabled man in oil patch killing

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Prosecutors say they no longer will pursue the death penalty against a Colorado man suspected of killing a teacher in eastern Montana's oil patch.

Tuesday's move by Richland County Attorney Mike Weber comes after psychiatrists determined 25-year-old Michael Keith Spell is mentally disabled.

Spell is charged with killing 43-year-old Sherry Arnold, who disappeared while jogging along a Sidney street in 2012.

Weber cited a 2002 U.S. Supreme Court ruling that said executing mentally disabled criminals constitutes cruel and unusual punishment.

A state judge on Friday rejected attempts by Spell's attorneys to have him declared incompetent. That would have let him avoid trial.

Spell now faces a maximum of life in prison if convicted on charges of attempted kidnapping and deliberate homicide.

An accomplice pleaded guilty in a deal with prosecutors.