AURORA, Colo. - The man accused in last Friday's mass shooting at an Aurora movie theater sent a notebook full of details about how he was going to kill people to a University of Colorado psychiatrist before the attack, reported Fox News.
The notebook was mailed to the professor and sat unopened in a mail room for as long as a week before it was found Monday.
FBI agents and police officers were called to the Anschutz medical campus on Monday morning on reports of a suspicious package that was sent from suspect James Holmes.
Although the package turned out to be harmless, a search of a campus services' mail room turned up another package sent to the psychiatrist with Holmes' name in the return address, Fox reported citing unmanned sources.
"Inside the package was a notebook full of details about how he was going to kill people," the source said. "There were drawings of what he was going to do in it -- drawings and illustrations of the massacre."
It is not clear why the package was sent to the psychiatrist. The notebook is now in the possession of the FBI.
Holmes is accused of killing 12 and injuring 58 at a midnight showing of the Batman movie "The Dark Knight Rises" at the Century 16 Theater in Aurora.
Police believe the attack was meticulously planned. Holmes had four guns with him during the shooting and had bought hundreds of rounds of ammunition, police have said.
During the attack, Holmes allegedly tossed a gas container into a crowded theater then fired a 12-gauge shotgun at the crowd. As panicked moviegoers ran for the exits, he allegedly switched to a .40 Glock pistol and a .223 Smith & Wesson M&P semi-automatic with a high-capacity drum clip, police said. The gun jammed, likely saving many lives.
Holmes is also suspected of booby-trapping his Aurora apartment with explosives and enough gas that would have consumed the building.
He is being held without bond in isolation in the Arapahoe County Detention Center on suspicion of multiple counts of first-degree murder.
During a Monday morning hearing, Holmes looked disheveled and despondent. He could face the death penalty.