The man accused of attacking a movie premiere in Colorado is being described as a "mellow" person, a doctoral student who had quit his medical program.
James Holmes, 24, was a resident of North Aurora, not far from the Denver-area theatre he is suspected of shooting up. Police on Friday were painstakingly examining his apartment, which is said to be so thoroughly booby-trapped that it could be days before it is safe.
A source told the Reuters news service that the traps have made it too unsafe to enter the apartment, and that police are now planning to detonate the traps using a robot late Friday night.
As a stunned public grapples with the question of what would motivate someone to carry out such an attack, little detail is emerging about Mr. Holmes.
"He was laid-back, kept to himself, never really talked to anybody," neighbour Melvin Evans told local reporters in a televised scrum. "He was somebody you wouldn't even look at twice walking down the street. Very, very mellow."
Local authorities say that the man had no record beyond a traffic citation. He was not on any police watch-lists and there is no suspicion that the attack was linked to terrorism.
Police said that Mr. Holmes is 6'3". One witness estimated his weight at between 85 and 90 kilograms, describing him as "muscular" but "slender." The shooter cut an imposing figure in the theatre, though, with witnesses saying he was clad in a bulletproof vest, helmet and gas-mask.
His mother appears to have concerns about her son. When the television station ABC reached her in California and informed her what had happened, she is reported to have said "you have the right person."
Mr. Holmes is reported to have studied neuroscience at the University of Colorado's medical campus but had recently decided to withdraw. Another report said that he quit last month. His reasons for leaving the program are not known.
The family released a statement in which they said they were "still trying to process" the situation and asked for privacy.
"Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved," the statement read. "Our family is cooperating with authorities in both San Diego, California and Aurora, Colorado."
With a report from Reuters.