Investigators have learned that James Holmes, the man accused of perpetrating the largest massacre in American history, had received a significant number of commercial deliveries to his home and office, as they try to build a picture of the alleged shooter and the events leading up to the largest mass shooting in American history.
"What we're seeing here is some evidence of calculation and deliberation," said Aurora Police Chief Dan Oates.
Bomb techinicians spent much of the morning making Holmes' Aurora, Colo., apartment safe to enter, and investigators then worked into the evening collecting evidence and securing the scene, said Jim Yacone of the FBI.
After 7 p.m. local time, residents in neighboring buildings were allowed back into their homes for the first time since early Friday morning, though tenants in Holmes' building will have to wait until Sunday.
"An extensive amount of evidence" is being collected and will be sent to the FBI's crime lab in Quantico, Va., Yacone said.
Authorities conducted a controlled detonation today as they slowly entered the booby-trapped apartment, which authorities said was "set up to kill."
"It was an extremely dangerous environment. If [someone] had walked in that door, they would have sustained significant injuries or lost their life," Yacone said.
A robot driven by a bomb technician and dynamic destruction tools were used to slowly and methodically disable explosive devices while also preserving evidence, Yacone said.
A loud pop was heard, but there was no visible smoke or fire at the scene. The street outside the apartment was shut down and residents were notified of the explosion by a reverse 911 call.
Police said Friday that a large number of explosive devices and trip wires were found at Holmes' apartment in an "elaborate" set-up.
One official told ABC News there were wires everywhere and described Holmes as a like a mad scientist.
Some devices appeared to be strapped to boxes of bullets and what looked like mortar rounds, police said.
The "flammable and explosive" materials could have blown up Holmes' apartment building and the ones near it, police said.
After a thorough search of Holmes' apartment, police moved into the investigation phase, hoping Holmes' computer -- if he has one -- and any writings could provide a gateway to understanding his motive.
A former doctoral student, Holmes is suspected of killing 12 people at the screening of the latest Batman movie in Aurora early Friday morning. Fifty-eight people were wounded.
Authorities have finished sweeping the Century 16 theater and plan to turn it over to Holmes' defense on Tuesday and back to theater owners on Wednesday, Oates said.
Personal belongings that were left behind amid the chaos and carnage were recovered by Aurora police, who plan to work with victims advocates to help reuunite people who were in the theater that night with their belongings, providing there is no forensic link, Oates said.
Among the dead include Micayla Medek, 23; Alex Sullivan, 27, who was attending the movie for his birthday; Ohio native Matt McQuinn; and Alex Teves, 24.
Two other people died at the hospital, including 24-year-old aspiring sportscaster Jessica Ghawi. Police said 30 people remained hospitalized with 11 of them in critical condition. Bullets from the shooting spree tore through the theater and into adjoining theaters, where at least one other person was struck and injured.