Next to the boom box outside his apartment, Gumbinner testified, Holmes said he placed a toy car and a device that looked like it would control the car but would instead have set off the explosives.
Authorities said they recovered the boom box, which bore Holmes' fingerprints. The remote-control car device was never found, Appel testified.
A series of self-portraits displayed in court, apparently made before Holmes allegedly left for the theater, according to data retrieved from his phone, show him in eye-blackening contacts, his tongue stuck out in one, flashing a toothy grin and a handgun in another.
Video from the theater shows a man they say is Holmes -- wearing dark pants, a light-colored shirt and a dark stocking cap covering his orange hair -- entering the multiplex before the movie begins.
The recordings show him going into Theater No. 9, a different theater from the one listed on his ticket.
Sources have said they believe he propped open the theater's back door and went to his car to put on body armor and arm himself. Authorities believe Holmes then re-entered the theater, tossing gas canisters before opening fire about 18 minutes into the movie, according to sources.
Witnesses who have spoken to CNN about the shooting have said the gunman roamed the theater, shooting randomly as people tried to scramble away or cowered between seats.
Among the 41 calls to 911, one stands out. In the 27-second call, at least 30 shots can be heard amid the chaos.
At some point, according to Pearson, one of Holmes' weapons jammed.
"Had the AR-15 not jammed, he would have killed more people," she said.
Investigators found 76 shell casings in the auditorium. Most of the spent rounds -- 65 -- were .223 caliber rifle rounds, six were shotgun shells and five were .40 caliber rounds from the Glocks, Appel said. Police also found one of the tear-gas canisters inside the theater, Appel said.
Also located was a large drum magazine for the rifle that appeared to have jammed, Sgt. Gerald Jonsgaard testified Monday.
Outside, the first officer to encounter Holmes -- who was dressed in body armor, a helmet and a gas mask as he stood near his car -- described him as unnaturally relaxed. In fact, from Holmes' appearance, Officer Jason Oviatt thought he was a fellow police officer.
A trail of blood led from the theater. The rifle that authorities say Holmes used in the attack lay on the ground near the building. Holmes was just standing there, Oviatt testified Monday.
"He seemed very detached from it all," Oviatt said.
Holmes, sweating and smelly, his pupils dilated, didn't struggle or even tense his muscles as he was dragged away to be searched, Oviatt said.
Police would cut off the body armor he wore and learn about the explosive booby-trap at his home.
Police described a strange scene in the interrogation room -- Holmes sitting in his underwear, T-shirt and white socks after police had cut away his body armor -- making puppets of the paper bags officers had placed over his hands to preserve gunpowder evidence, according to Appel.
Holmes played with his polystyrene drinking cup as if it were a piece in a game. Appel said. Then he removed a staple from the table and tried to stick it in an electrical outlet, the detective testified.
Asked by a defense attorney whether he had ordered a blood test for Holmes, Appel said he had not.
"There were no indications that he was under the influence of anything," he said.