AURORA, Colo. — The situation was literally explosive in this grieving Denver suburb Saturday as bomb experts disarmed the booby-trapped apartment of James Holmes, who police said spent months amassing explosives, weapons and ammunition and then walked into a movie theater early Friday and began shooting.

The failed neuroscience student, who is scheduled to appear in court Monday, remains an enigma — a young man who, despite troubles in academia so severe that he was quitting his graduate school program, showed no obvious sign of being on the brink of extreme violence.

The police chief, Dan Oates, said he and his officers felt targeted by the elaborate network of explosives in Holmes’s apartment.

“This apartment was designed, I say, based on everything I’ve seen, to kill whoever entered it,” Oates said at a news briefing. “It was gonna be a police officer, okay? Make no mistake about what was going on there. You think we’re angry, we sure as hell are angry.”

Aurora police said Saturday night that all explosives had been removed from the apartment and that FBI agents had gone inside to examine other evidence.

The protracted bomb-squad work at Holmes’s apartment took place on a day when Aurora residents learned the names of the 12 people killed and 58 wounded in the assault at the Century 16 movie theater, where a crowd of mostly young people showed up for the midnight screening early Friday of the new Batman film, “The Dark Knight Rises.”

Among the dead were two members of the military, a man celebrating his 27th birthday and a 6-year-old girl, Veronica Moser-Sullivan, whose 25-year-old mother, Ashley Moser, is in critical condition and semiconscious with multiple gunshot wounds to her throat and abdomen.