The suspect in a mass shooting at a Colorado movie theater dropped out of medical school last month.

Spokeswoman Jacque Montgomery says 24-year-old James Holmes was a student at the University of Colorado School of Medicine in Denver until last month. She did not know when he started school or why he withdrew.

Holmes is accused of killing a dozen people when he fired into a crowded movie theater in the Denver suburb of Aurora. He was wearing a gas mask and set off an unknown gas in the theater.

Holmes is in police custody, and the FBI says there is no indication the attack is tied to any terrorist groups.