Colorado shooting suspect James Eagan Holmes makes his first court appearance in Aurora, Colorado, on Monday.

Centennial, Colorado - The man accused of killing a dozen people in a Colorado movie theatre during a showing of the new Batman movie made his first court appearance on Monday, looking drowsy and emotionless, his hair dyed shades of orange and red.

James Eagan Holmes, 24, who was detained immediately after the massacre, appeared groggy during the brief hearing, looking straight ahead and occasionally closing his eyes as if fighting off sleep. He was shackled at the wrists and ankles.

About 40 members of the victims' families were seated on the left side of the courtroom. One family member seated in the front row glared at Holmes throughout.

When Arapahoe County District Judge William Sylvester asked Holmes a question, he remained expressionless and an attorney answered for him.

Police say he presented a far different figure last Friday when, dressed in a gas mask and body armour and toting three guns, he opened fire at a packed midnight show at a theatre complex in the Denver suburb of Aurora in the early hours.

The dead include war veterans, an aspiring sportscaster who had narrowly escaped a shooting in a Toronto mall earlier this summer, and a six-year-old girl. Fifty-eight other people were wounded, and many of them have serious injuries.

The former neuroscience student also left his apartment booby-trapped with explosives that police said could have destroyed the apartment complex. They conducted a controlled detonation over the weekend.

Police say they are still searching for a motive for the crime, which baffled fellow students and acquaintances. They described Holmes, a native of San Diego, as a quiet high-achiever whose past gave little inkling that anything was amiss.

At the hearing the judge set a date of next Monday for formal charges to be filed.

Arapahoe County District Attorney Carol Chambers said she would consult with the victims and families of the dead before making a decision on seeking the death penalty.

Chambers, who has prosecuted two of the three inmates now on Colorado's death row, told reporters outside the court house that the decision on the death penalty had to be made within 60 days of his arraignment, “so it's months down the line”.

The crime meets all the elements of Colorado capital case law, including premeditation, multiple victims, and the killing of a child, said former Denver prosecutor Craig Silverman.

“If James Holmes isn't executed, Colorado may as well throw away its death penalty law,” he said.

“I think the death penalty would be justice,” said David Sanchez, whose son-in-law Caleb Medely, 23, was shot in the head while attending the movie with his wife, Katie Medely, who is Sanchez's daughter. She is nine months pregnant.

“When it's your own daughter, and she escaped death by mere seconds, it really makes you angry,” Sanchez said outside the court house. He had come for the hearing but was not able to get into the courtroom.

It was not clear if any of Holmes' family attended the hearing, but a California lawyer retained by the family, Lisa Damiani, was scheduled to make her first formal statement on the case later on Monday.

The press conference by attorney Damiani was scheduled for 1pm PDT (20h00 GMT), her office said. Damiani was expected to speak outside her offices in San Diego, California.

Holmes and his motives remained largely a mystery, with past associates saying he displayed no hints of a mental illness or violent tendencies.

He was armed with a Smith & Wesson M&P .223 semi-automatic rifle, similar to an AR-15 assault rifle, a 12-gauge shotgun and a Glock .40-calibre handgun. Police found an additional Glock .40-calibre handgun in his car. All the weapons had been bought legally.

He is in solitary confinement to protect him from other prisoners. Holmes had recently dropped out of a doctoral degree programme in neuroscience at the University of Colorado's Anschutz Medical School, a few blocks from his apartment. - Reuters