Months of 'calculation and deliberation' before Aurora murders:Cops

Deliveries received by the man accused of committing a movie house massacre at a Denver-area premiere of the new "Batman" film suggest months of "calculation and deliberation" leading up to the shooting rampage that killed 12 people, police said.

Aurora Police Chief Dan Oates discussed the shipments as local and federal authorities completed the painstaking process of disarming suspect James Holmes' apartment, which was found booby-trapped with explosive devices after the shooting at a multiplex theater several miles away.

On Saturday, the local coroner's officer released the names of the 12 people killed. As evening fell, residents gathered at a local high school to mourn the passing of a classmate who graduated in May.

"We've become aware that the suspect over the last four months received a high volume of deliveries to both his work and home addresses," Oates said. "This begins to explain how he got his hands on all the magazines and ammunition.

"We also think it begins to explain some of the materials he had in his apartment," Oates said. "What we're seeing here is evidence of some calculation and deliberation."

A gunman wearing a full suit of tactical body armor, helmet and gas mask opened fire at a packed midnight showing of "The Dark Knight Rises" early on Friday morning, killing 12 people and wounding 58. Holmes, 24, was arrested minutes later in a parking lot behind the cinema.

When police arrested Holmes, he was armed with an AR-15 assault rifle, a 12-gauge shotgun and a Glock .40-caliber handgun, Oates said. Police found an additional Glock .40-caliber handgun in his car, parked just outside the theater's rear emergency exit, he said.

Police said Holmes had purchased the weapons legally at three area gun stores in the last 60 days and bought 6,000 rounds of ammunition online, including a 100-round drum magazine for an assault rifle.

Among the dead were a 6-year-old girl who had just learned to swim, a young man celebrating his 27th birthday and an aspiring sportscaster who missed by minutes being on the scene of a Toronto mall shooting earlier this summer.

The mass shooting stunned the nation, evoking memories of the 1999 massacre at Columbine High School in Littleton, 17 miles from Aurora, where two students opened fire and killed 12 students and a teacher.

It also reverberated in the U.S. presidential race. Both President Barack Obama and his Republican rival, Mitt Romney, toned down their campaigns on Friday, pulled ads from Colorado and dedicated scheduled events to the victims.

Obama was scheduled to travel to Colorado on Sunday to honor the shooting victims, an administration official said.

Arapahoe County Sheriff Grayson Robinson said the suspect was being held in solitary confinement to protect him from other prisoners, a routine move in high-profile cases.

Holmes, who authorities said had dyed his hair red and called himself "the Joker" in a reference to Batman's comic-book nemesis, was due to make an initial court appearance on Monday.

Little has surfaced from Holmes's past to suggest he was capable of such violence.

Until last month, he was studying for a doctoral degree in neuroscience at the University of Colorado's Anschutz Medical School, a few blocks from his apartment.

A top student, he had earned a prestigious federal grant from the National Institutes for Health to support his studies. The grants are intended for "outstanding neuroscientists and academicians who will make significant contributions to neurobiology," university spokeswoman Jacque Montgomery said.

Holmes had spent a year in the doctoral program, where a fellow student described him as quiet and studious, before he abruptly withdrew from the university last month. He gave no reason for his departure.

Holmes kept a low profile off campus as well. He was not active under his own name on social media sites like Facebook and both the landlord and fellow tenants of his red-brick apartment building said they knew little about him.