James Holmes, the man accused of opening fire at the jam-packed Denver premiere of 'The Dark Knight Rises', was a recipient of federal grant to study neuroscience, according to the University of Colorado.

The University's spokeswoman Jacque Montgomery said Saturday that Holmes was one of six neuroscience students at the school to get National Institutes of Health grant money. Apparently, the grants are intended for "outstanding neuroscientists and academicians who will make significant contributions to neurobiology".

Holmes, 24, graduated with honors from the University of California-Riverside with a degree in neuroscience in Spring 2010. He enrolled at the University of Colorado for the program in June 2011 and was in the process of "withdrawing" from the study during the shooting, according to the spokeswoman. Holmes graduated in 2006 from Westview High School in San Diego.

Montgomery also added that he had taken an oral exam at the end of the semester that all students must pass to continue in the program.

According to the School website, the University's graduate neuroscience program students are "highly motivated and typically have very strong credentials for admission".

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

He surrendered to police without any fight and alerted them to the presence of explosives in his apartment, a University-managed building 5 miles from the suburban Denver theater, police said. In the news conference, Aurora Police Chief Dan Oates confirmed that Holmes had rigged his apartment with "chemical and incendiary devices."

New York Police commissioner Ray Kelly said at a press conference that Holmes had dyed-red hair and said that he was "The Joker," the arch-nemesis of Batman, during the shooting.

The classmates and neighbors of the suspect describe him as quiet, smart and a quick learner. They say they are as shocked as the rest of the nation and have no clue about what might have "triggered" him to commit such an act.

The mass shooting has evoked 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.