The battle over what evidence can be used against Colorado theater shooting defendant James Holmes is turning to the testimony of bomb technicians and explosives experts.

Hearings resume Tuesday.

Holmes pleaded not guilty by reason of insanity to charges of killing 12 people and injuring 70 in 2012. At pretrial hearings this month, prosecutors and defense lawyers are trying to persuade the judge to allow or throw out statements Holmes made to police and other evidence. Most of the evidence could be used to bolster or weaken the insanity claim.

Holmes faces murder and attempted-murder charges. His lawyers acknowledge he was the shooter, but they say he was in the grip of a psychotic episode.

Prosecutors are seeking the death penalty, but they must convince jurors that he was sane.