New evidence is being presented in a pre-trial hearing for the man accused of carrying out the Colorado cinema massacre in July last year.
James Holmes is accused of opening fire in a cinema in Aurora, Colorado - killing 12 people and injuring 58 more.
A judge will determine at the end of the week-long hearing whether the 25 year old will face trial on more than 160 counts of murder, attempted murder, and firearms offences.
The alleged gunman was 'relaxed' and compliant when arrested after the massacre in which 12 people were killed, an officer has told a court hearing.
James Holmes, who was wearing body armour and a mask, told police his name and volunteered that there were improvised explosive devices rigged up in his apartment, when detained after the shooting in July last year in Aurora, Colorado.
Holmes, sporting dark brown hair and a full beard, was led into court in handcuffs at the start of a week-long hearing expected to hear more details about the shooting, which revived America's perennial debate over gun control.
Clad in dark red prison scrubs, Holmes - who had bright orange hair when he first appeared in court last July - stared straight ahead and talked to no one in the courtroom, as relatives of the victims looked on.
Aurora policeman, Jason Oviatt, told the court how he at first thought Holmes was another officer when he arrived with dozens of other police, in response to emergency calls about the midnight shooting at a screening of the new Batman film.
Holmes had his hands on the top of a white car at the back of the building, and as Oviatt approached he saw he was not a fellow officer.
'As I got closer the man was just standing there, not moving. The overall picture didn't match a police officer as I got closer,' said Officer Oviatt, one of two officers who testified at the opening court session.
The 25-year-old offered no resistance when ordered to put his hands up, he said.
'He was completely compliant ... He was very relaxed, there weren't normal reactions to anything ... He was very detached,' he said, adding: 'He seemed to be out of it, and disoriented.'
Fellow policeman, Aaron Blue, said Holmes told officers his name, home address, and that he had four weapons. 'He volunteered there were no bombs here, but he had improvised explosive devices at his home,' he said.
The attack took place on July 20 in an opening midnight screening of the blockbuster Batman movie, The Dark Knight Rises, at the Century 16 theater in Aurora.
Witnesses said Holmes threw smoke bomb-type devices before opening fire randomly with weapons including an AR-15 rifle, a 12-gauge shotgun and a .40-calibre pistol.
His one-bedroom apartment was later found to be booby-trapped with an array of home-made explosive devices, which police had to disarm before entering the dwelling.
