AURORA - Suspected mass murderer James Eagan Holmes left a collection of explosives and gasoline-filled bottles in his apartment that would have incinerated the third floor and turned the building into an inferno.

Holmes had stuffed approximately 30 plastic shells used in aerial fireworks with gunpowder, turning them into grenades, filled glass jars with gasoline and gunpowder, and had 10 gallons of gasoline on hand, some of it in bottles, said a law enforcement source close to the investigation.

The gas would have fed flames, dramatically increasing the damage from any explosion.

"The majority of it was in the living room," the source said.

Bomb squad members disabled the explosive devices Saturday, after eliminating the threat from a control box using water as a "force hammer" to blow it up.

The box was attached to a trip wire that would cause it to detonate.

"We do not yet know how the 30 grenades" were rigged to explode, the source said. "We know it is electrical in some manner but need further investigation."

The bomb squad and investigators removed the explosives after disabling the control box.

They placed the bombs in a dump truck filled with sand. The truck was taken to a remote area east of Denver and the contents blown up, the source said.

Residents of the three-story brick apartment building at 1690 Paris St., where Holmes lived, were not allowed to return home Tuesday as they

expected.

Holmes' neighbor from across the hall was not comfortable giving his name for publication, but said he was frustrated by the lockout.

He watched Holmes on TV on Monday during the suspect's first court appearance for the shooting. "He looked crazy. I've never seen him look like that before."

Prosecutors visited the site at around 2:30 p.m. Tuesday after FBI agents spent the morning photographing, and examining the contents of Holmes' apartment on the third floor.

Some books remained on a case in one of the rooms of the 800-square foot apartment during the prosecutors' visit, along with a poster on Holmes' wall.

Over the weekend, police and other officials speculated the investigation of Apartment 10 would be complete by Tuesday morning, but crews continued to work.

Residents were evacuated early Friday morning after Holmes allegedly killed 12 people and injured 58 others who were watching the premiere of "The Dark Night Rises" at the Century Aurora 16 theater. As he was arrested, Holmes told police there were explosives in his apartment. The front door had been rigged with a device that Aurora Police Chief Dan Oates said was intended to kill whomever opened it.

Residents of the complex who returned Tuesday were turned away by Aurora police.

Police guarding the building said the investigation was ongoing and had no timetable for when residents could return.

The parking lot below Holmes' third-floor unit is still littered with glass from police breaking the windows in order to disarm the bombs at a safe distance.

The back doors of the building also remain off their hinges.

Tom McGhee: 303-954-1671, tmcghee@denverpost.com or twitter.com/dpmcghee

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