The neuroscience graduate student suspected of Friday's mass shooting in a Colorado movie theater had mailed a notebook with drawings of a massacre to a University of Colorado psychiatrist, but the package wasn't opened until after the deadly attack, according to a law-enforcement official.

James Holmes, a 24-year-old Ph.D. student at the university, is suspected of a shooting rampage that killed 12 and wounded 58 people at a midnight showing of the newly released Batman movie in Aurora, Colo.

Mr. Holmes didn't speak at a hearing in Colorado court on Monday, where he appeared with a dazed expression and his hair dyed red-orange. He is expected to be formally charged at a hearing on July 30. Prosecutors are weighing whether to pursue the death penalty, which is rarely sought in the state.

After Friday's attack, authorities discovered an unopened package in the mailroom at the University of Colorado that was mailed by Mr. Holmes to a psychiatrist, according to the law-enforcement official. The drawings in the notebook apparently represented Mr. Holmes's plans, the official said.

Fox News reported the existence of the notebook on Wednesday. It couldn't immediately be determined when the package was sent, to whom it was addressed or why it hadn't been delivered.