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FBI: James Holmes' booby-trap used remote-control car, frying pan

There was more gruesome testimony as the pretrial hearing continued for James Holmes the lone gunman in the Aurora theater shooting that killed 12 and injured 58 others. And for the first time, in words attributed to Holmes, a detailed description of what he expected would happen when he left for the theater complex with four guns and hundreds of rounds of ammunition. NBC's Mike Taibbi reports.

Updated at 11:21 p.m. ET: After two days of presenting evidence against accused Aurora theater shooter James Holmes, the prosecution prepared to interview a detective, its final witness, on Wednesday, according to the Denver Post. The defense may then set forth its case. 

Among the more vivid accounts in Tuesday's testimony was the description of how Holmes booby-trapped his home, hoping to distract officers from the theater shooting. 

Holmes used a thermos, frying pan, remote-control car and volatile chemicals to rig his apartment to blow up during the Aurora theater massacre, an FBI agent testified Tuesday.

On the stand for a preliminary hearing, bomb technician Garret Gumbinner described the diabolical contraptions authorities found when they went to the grad-school dropout’s Colorado apartment.

There was a trip-wire leading from the door to a thermos filled with glycerine that was perched over a frying pan filled with potassium permanganate, Gumbinner said.

If they combined, there would be a spark that would set off a chain-reaction: fast-moving flames and a series of explosions as homemade devices scattered around the apartment ignited.

Thomas Cooper / Getty Images file

Police break the window of the apartment of of James Holmes, the suspect of in the Aurora, Colo., movie theater shooting on July 20.

On top of the fridge was a remote-controlled “pyrotechnic” box filled with 6-inch fireworks shells. Holmes left the remote for it outside, in a trash bag with a toy car and a boom box on a timer, the agent said.

His fantasy was that someone on the street would hear the music, open the bag, decide to play with the car, fiddle with the remote and detonate the explosives, Gumbinner said.

In all, there were more than a dozen explosive devices in his apartment loaded with napalm, smokeless powder and live ammunition. Carpets were soaked with oil and gasoline to fuel any blast.

His computer was set to play loud music at a designated time. He was hoping “someone would call the police and that the police would respond to his apartment,” Gumbinner said.

"He said he rigged his apartment to explode or catch fire in order to divert police resources to his apartment,” Gumbinner said, recounting an interview with Holmes.

No one played with the toy car or banged on the door, though. And when Holmes was arrested outside the Century 16 multiplex – after allegedly killing a dozen people and wounding 58 – he quickly told police about his traps.

The scope of the bizarre setup was revealed during the second day of a hearing to determine whether there is enough evidence to put the neuroscience scholar on trial for first-degree murder.

A parade of law-enforcement officials took the stand to describe Holmes’ painstaking preparations and the horrific aftermath of the July 20 shooting at the Century 16 multiplex – but there was no mention of motive.

The picture they presented was of a methodical killer who left nothing to chance and foreshadowed his own fate in a question posted to two online dating-service profiles: “Will you visit me in prison?”

Courtesy the family via KUSA

Veronica Moser-Sullivan, in an undated family photo.

Holmes bought his ticket, through Fandango, 12 days before the opening of the Batman flick “The Dark Knight Rises,” police testified, though it emerged that he was supposed to see it in Theater No. 8, not No. 9 where the ambush took place.

With so much evidence against their client, Holmes’ legal team is expected to mount an insanity defense, and his attorneys tried to highlight his state of mind at several points during the day’s testimony.

They questioned Aurora Police Department Detective Craig Appel about why Holmes wasn’t tested for drugs or alcohol even though his pupils were hugely dilated and he acted strangely after his arrest.

'Help me!': Teen's 911 call played at Holmes hearing

Appel told the court that police had placed paper bags over Holmes’ hands to preserve gunpowder residue, and he pretended they were puppets. He also ripped a staple out of a table and tried to stick it in an electrical socket.

Earlier, the defense asked an agent from the Bureau of Alcohol, Tobacco and Firearms whether there is any legal process in Colorado to stop a “severely mentally ill” person from buying guns or ammunition.

The agent had just ticked off the items Holmes legally purchased in the two months before the rampage, including two handguns, a shotgun, a rifle, more than 6,200 rounds of ammunition, body armor, chemicals, fireworks and practice targets.

Holmes – wearing a beard and jail jumpsuit and looking disheveled – showed little reaction to any of the testimony.

He simply stared straight ahead when prosecutors played a heart-breaking 911 tape of a 13-year-old girl pleading for help for her mortally wounded 6-year-old cousin, Veronica Moser-Sullivan.

Veronica’s father, Ian Sullivan, wept with his eyes closed as he listened for four long minutes to the chaos that marked his daughter’s final moments.

The day’s proceedings ended with Sgt. Matthew Fyles reading a grim catalog: the name of every person wounded and the nature of their injury.  When he got to Ashley Moser – who suffered a miscarriage, was paralyzed and lost her daughter, Veronica – he choked up.

Wednesday is scheduled to start with the prosecution calling a detective as its final witness, according to the Denver Post. The defense could then call its own witnesses.  

NBC News’ Mike Taibbi and KUSA contributed to this report.

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