State prosecutors say a Colorado man's reported attempts to manipulate staff at the state psychiatric hospital prove he was competent to plead guilty to killing an eastern Montana teacher.

The state responded this week to Michael Spell's appeal of his conviction and 100-year prison sentence in the January 2012 death of Sherry Arnold of Sidney. The appeal argues the Parachute, Colorado man is mentally disabled and should be placed at the Montana State Hospital.

The judge found him competent to stand trial after giving more credibility to the findings of a 60-day state hospital evaluation than shorter evaluations by defense experts.

A psychiatrist testified Spell could control his behavior to earn privileges at the hospital and that his psychiatric complaints seemed to increase after he learned which symptoms could lead to a finding of guilty but mentally ill.