Aurora Shooting Suspect James Holmes In Court

The student accused of a shooting which left 12 dead and dozens wounded at a Batman film screening appeared "out of it" when he was arrested, a court has heard.

Prosecutors have begun outlining the case against James Holmes, who is accused of opening fire during a showing of The Dark Knight Rises in the Denver suburb of Aurora.

The week-long preliminary hearing in Centennial, Colorado, will determine whether there is enough evidence to put him on trial on more than 160 counts of murder, attempted murder and firearms offences.

One of the first police officers who arrived at the scene of the shooting told the court he initially thought Holmes was a policeman, due to the combat gear and gas mask he was wearing.

Jason Oviatt said it was only when he saw everyone else fleeing apart from the masked man that he approached him.

He said Holmes simply stared into space, appearing "out of it" with hugely dilated pupils. He also said the gunman was dripping with sweat and smelled badly.

Another office described how he almost slipped on the "huge amount of blood" as he entered the Century 16 cinema.

Justin Grizzle, a former paramedic, took six critically injured victims to hospital in his car and testified that he could hear "blood sloshing around in the back" as he turned corners.

Sergeant Gerald Jonsgaard, one of the first officers on the scene, described finding six-year-old Veronica Moser-Sullivan, the youngest victim.

"She had been carried down from the top to the front of the theatre. I checked for a pulse. She was dead," he said. A colleague said he felt a pulse, but the child was declared dead on arrival in hospital.

The court was also shown clips of a security video in which Holmes could be seen entering the cinema with an electronic ticket purchased on July 8 before heading into Theatre 9, where the shootings took place.

Survivors and relatives were in court for the hearing after being warned to expect harrowing details.

Holmes, who previously cut a bizarre figure in court with bright red hair, stared straight ahead and spoke to no one throughout the hearing. He now has dark hair and a full beard.

He could face the death penalty if convicted, but his lawyers are expected to plead insanity if the case goes to a full trial.

A promising neuroscience student, he began to stock up on weapons, ammunition, explosives and combat gear in the spring of last year. He began to see a university psychiatrist and then dropped out of his course.

The Aurora rampage was one of a number of mass shootings in the US last year, culminating with the killings at Sandy Hook Elementary School in Connecticut, which have raised the issue of gun control.

A review ordered by President Barack Obama is due to report back within weeks, but the gun lobby has signalled it will oppose new restrictions.