The man accused of killing 12 people and wounding 58 others in a Colorado movie theater made his first court appearance Monday, as investigators continue to piece together the events leading up to the shooting.

James Holmes, his hair dyed bright orange, appeared unemotional and at times sleepy in Monday's appearance. He did not speak, staring at the floor or straight ahead as the judge told him there was probable cause to charge him with first-degree murder.

The judge ordered that Holmes be held in detention until next Monday, when he is due back in court to be formally charged. The prosecutor's office says it is considering pursuing the death penalty.

Holmes has been held in solitary confinement since police arrested him early Friday outside the theater in Aurora, Colorado, near Denver. Authorities say he is refusing to talk about what prompted him to open fire on a crowd watching the film The Dark Knight Rises.

The shooting has renewed gun control debates in the United States, particularly about the lack of regulation on buying ammunition online. Authorities say Holmes bought thousands of bullets from websites in the months leading up to the attack. Proponents of such sales say it is legitimate for sportsmen to buy large amounts of ammunition that way.