A judge in Colorado has ordered movie theater shooting suspect James Holmes to remain in jail until his next court appearance when he likely will be formally charged.

Prosecutors say they are considering pursuing the death penalty for Holmes, who allegedly killed 12 people and wounded 28 at a midnight Friday screening of the new Batman film The Dark Knight Rises.

Holmes, with his hair dyed bright orange, said nothing and looked dazed and unemotional during his first court appearance on Monday. The judge informed him that he could be facing first degree murder charges.

Authorities are still trying to figure out who Holmes is and what turned a brilliant PhD student in neuroscience into a suspected mass murderer. Investigators say he is refusing to talk.

Holmes allegedly tossed a tear gas bomb into the theater before shooting at the audience with a variety of guns. Police arrested him without a fight in the parking lot.

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.