July 25, 2012— -- Accused movie theater shooter James Holmes may have mailed a notebook to his school detailing his plans to carry out a massacre, sources say.
The notebook that is believed to have been written by Holmes was mailed to the University of Colorado, where Holmes had been a student until dropping out last month, ABC News has learned.
Fox News reported that the notebook was mailed to a specific psychiatrist at the university and that it contained "full details about how he was going to kill people, drawings of what he was going to do in it, and drawings and illustrations of the massacre."
There are conflicting reports on whether the notebook arrived at the university before or after the massacre, but it was found on Monday during a search of the mailroom, ABC News learned today.
Holmes is believed to have walked into the Aurora, Colo., theater dressed in riot gear and brandishing at least three weapons at the front of "The Dark Knight Rises" movie premiere around midnight on Friday. He allegedly set off two smoke bombs before opening fire on the movie theater patrons with an assault rifle, shotgun and a handgun.
The university has not confirmed the existence of the note, but issued a statement saying that the "Colorado Anschutz Medical Campus can confirm that the suspicious package discovered at the Facilities Services building on Monday, July 23, 2012, was delivered to the campus by the United States Postal Service that same day."
Discovery of the package prompted the evacuation of the building for about 90 minutes starting at 12:26 p.m., the school said.
The school also refused to say whether Holmes was seeing a psychiatrist. Campus officials have insisted they handled the Holmes case correctly.
"To the best of our knowledge, we did everything we should have done," the statement read.
The detail of the mailed notebook adds to other information emerging about Holmes' troubles at the University of Colorado, where he spiraled down from a successful and apparently happy student to an accused mass murderer in a matter of months. He reportedly struggled academically in the PhD program he enrolled in last fall.
On June 7, hours after he took a key oral exam which, according to ABC News affiliate KMGH, he failed, Holmes went out to a sporting goods store and bought a high-powered rifle, adding it to his growing arsenal.
Three days later he withdrew from the PhD program with no explanation.
Experts have told ABC News that it's possible Holmes has a mental illness that was exacerbated by the stress of failure.
Holmes was arrested in the parking lot outside the Aurora theater after the shooting. He was wearing a gas mask, bullet proof helmet and vest, and all black clothing, and told the police that he was the "Joker," a character from the Batman movie, "The Dark Knight."
Holmes will be arraigned July 30 in Aurora District Court.