CENTENNIAL, Colo. — A police officer testified at a preliminary hearing Monday that when he responded to emergency calls about a mass shooting at a crowded movie theater in Aurora, Colo., this summer, he found the suspected gunman standing calmly outside his car in a parking lot.
The arrest was made just moments after the man had allegedly opened fire inside, killing 12 people and injuring 58 others.
‘‘He was very relaxed,’’ said the police officer, Jason Oviatt. ‘‘It was like there weren’t normal emotional responses to anything. He seemed very detached.’’
The suspect, James E. Holmes, didn’t resist arrest behind the theater and volunteered that his apartment had been booby-trapped, Oviatt said.
Oviatt said that because Holmes had been wearing a helmet and a gas mask, he had first thought that he was a fellow police officer. “He was just standing there,’’ said Oviatt, as panic-stricken people fled the theater as quickly as they could, many with bullet wounds, some covered in blood.
But after a few moments, Oviatt realized that aside from his calm demeanor, there was something else dangerously amiss about the man, whom he had first seen standing perfectly still — his hands were oddly positioned on the roof of his white car. Then, as he placed the compliant Holmes into handcuffs, the officer found a handgun on the roof of the car where Holmes’s hands had been.
While frisking Holmes, he said, he found that he was swathed in layers of body armor, which officers eventually had to cut off with knives to search him adequately.
Police officers were among the first people to testify at a weeklong court hearing that will determine whether there is sufficient evidence to move the case against Holmes to trial, a decision that will be made by William Sylvester, a district judge in Arapahoe County.
But for victims and their families, the hearing may offer the best, and perhaps only, opportunity to understand how the July 20 shooting unfolded, and to get a glimpse into Holmes’s actions and mindset in the weeks before the attack.
A criminal trial — if one ever convenes — remains months away, probably after a series of legal arguments, including over Holmes’s mental fitness to stand trial.
It has been more than five months since Holmes, a former neuroscience graduate student, was accused of striding into a midnight screening of ‘‘The Dark Knight Rises’’ at a movie theater in an Aurora shopping mall and began shooting.
He faces more than 160 counts of first-degree murder and attempted murder.
On Monday, police officers described the scene inside the theater in graphic terms, describing amounts of blood on the floor so copious that they had trouble keeping their footing. As the movie played on and cellphones rang incessantly, the officers said, they went from person to person, checking for signs of life. “They were screaming, they were yelling: ‘Help us! Help us!’ ’’ said Justin Grizzle, a police officer who was among the first to respond.
Realizing there were not enough ambulances to transport the injured to hospitals, the officer said, he began putting people in his patrol car. He made four trips to the hospital, he said.
Lawyers for Holmes, 25, have signaled that they might call witnesses this week to discuss his mental state in the hope of rebutting the prosecution’s evidence that Holmes spent months methodically buying 6,000 rounds of ammunition, handguns, a shotgun, and an assault rifle.
Although Holmes has not yet filed a plea, his lawyers have said several times that he is mentally ill. Holmes had seen a psychologist at the University of Colorado, Denver, where he had been a graduate student and had so alarmed his doctor that she contacted the campus police about him.
Less than a month before the shooting, after he had dropped out of his neuroscience program, Holmes sent a text message to a classmate that suggested he believed that he suffered from dysphoric mania, a bipolar condition that combines manic behavior and dark, depressive tendencies.
Holmes warned the classmate to stay away from him ‘‘because I am bad news,’’ the classmate has said.