A law enforcement official says investigators have found a Batman mask inside the apartment of the Colorado shooting suspect who opened fire at a midnight premiere of "The Dark Knight Rises."
The official spoke to The Associated Press on Sunday on condition of anonymity because he was not authorized to speak to the press.
Authorities say they cleared dangerous materials from the apartment of 24-year-old James Holmes over the weekend after he allegedly set booby traps inside.
Holmes was arrested Friday after authorities say he opened fire during a midnight screening of "The Dark Knight Rises," killing 12 people and injuring dozens of others. He has been appointed a public defender and is scheduled to make an initial court appearance on Monday.
Aurora Police Chief Dan Oates says it could take months to determine a motive and police are working with FBI behavioral analysts.