James Holmes, accused of killing 12 people and wounding 70 by shooting up a Colorado movie theater, is challenging the use of fingerprint testimony at his criminal trial. Holmes, 26, faces 152 counts associated with firing an automatic weapon inside a Century theater in Aurora during the midnight premiere of a Batman movie, “The Dark Knight Rises,” July 20, 2012.

A hearing is set for Monday before Arapahoe County Judge Carlos Samour on a motion filed by Holmes’ attorneys arguing fingerprint testimony should be excluded because the evidence is unreliable. Their petition claims there are “no known error rates for either the techniques used in performing fingerprint analysis or the labs and techniques conducting the testing,” Courthouse News Service reported.

Earlier, Holmes’ attorneys sought to have expert testimony on ballistics and chemicals excluded. Samour rejected those motions (PDF), Courthouse News said.

Holmes’ trial is scheduled to start Dec. 6. He has pleaded not guilty by reason of insanity.

At the time of the mass shooting, the assailant tossed several gas or smoke canisters into the theater and then opened fire. Holmes was arrested outside the movie theater just moments after the shooting, and several guns were recovered from his vehicle. Investigators said Holmes had dyed his hair orange and called himself The Joker, one of Batman’s numerous nemeses.

Holmes' apartment was booby-trapped. Explosives experts were called in to remove the threat.