AURORA — The University of Colorado said Sunday it was investigating whether shooting suspect James Holmes used his position as a graduate student to order materials in the potentially deadly booby traps that police said they found in his apartment.
Holmes, 24, got deliveries over four months to his home and school, authorities have said. The university is looking into what was received at the school to assist police with their investigation, said spokeswoman Jacque Montgomery.
The suspect was described as a budding scientist, brimming with potential, who pursued a graduate program even as he planned the attack with "calculation and deliberation," police said.
Investigators spent hours Saturday removing explosive materials from inside Holmes' apartment a day after police said he opened fire and set off gas canisters in a movie theater minutes into a premiere of the "The Dark Knight Rises." The massacre left 12 people dead and 58 injured.
His apartment was booby trapped with jars of liquids, explosives and chemicals that could have killed "whoever entered it," Aurora Police Chief Dan Oates said, noting it would have likely been one of his officers.
Inside the apartment, bomb technicians neutralized a "hypergolic mixture" and an improvised explosive device containing an unknown substance, said James Yacone, an FBI special agent. There also were containers of accelerants, creating "an extremely dangerous environment," he said.
Oates said on CBS' "Face the Nation" that he had never seen a booby trap as elaborate as what was found in the apartment.
By late Saturday afternoon, all hazards had been removed from the apartment and residents in surrounding buildings were allowed to return home, police said.
The exception was Holmes' apartment building, where authorities were still collecting evidence. Authorities covered the windows of Holmes' apartment with black plastic to prevent anyone from seeing in. Before they did, a man in an ATF T-shirt could be seen measuring a poster on a closet that advertised a DVD called "Soldiers of Misfortune." The poster showed several figures in various positions playing paintball, some wearing masks.
Police left the apartment building carrying a laptop computer and a hard drive about 8 p.m. Saturday.
Holmes was in solitary confinement for his protection at a Denver-area county detention facility, held without bond on suspicion of multiple counts of first-degree murder. He was set for an initial hearing on Monday and has been appointed a public defender.
President Barack Obama was scheduled to travel to Colorado on Sunday to visit with the families of victims. The city of Aurora planned a vigil to remember the dead and wounded in the shooting later in the evening.
Among the dead was a 6-year-old girl and a man who died on his 27th birthday and a day before his wedding anniversary. Families grieved and waited at hospitals, with police reporting 11 people still in critical condition as of Saturday.
While authorities continued to refuse to discuss a possible motive for one of the deadliest mass shootings in recent U.S. history, details about Holmes' background as a student and would-be scientist trickled out.