Defense experts say a Colorado man seeking to avoid trial in the murder of a Montana teacher has a distorted recollection of past events and the mental capacity of an 11-year-old.

Two psychologists appearing for the defense told a Sidney, Mont., courtroom Monday that 24-year-old Michael Keith Spell is unfit for trial in the January 2012 killing of local teacher Sherry Arnold.

However, testimony also revealed that doctors at Montana State Hospital suspected Spell was faking it when he could not answer some questions during an evaluation.

Prosecutors are expected to call the state doctors to the stand Tuesday when Spell's competency hearing continues.

A co-defendant has pleaded guilty.

The case has highlighted the social costs of a Northern Plains oil boom that drew the defendants to the region looking for work.