Holmes' purchases were split between two planned attacks, prosecutors said — the theater shooting and a booby trapped apartment that would've blown up if anyone had entered.
The bottle of glycerin was meant to fall into the permanganate when the door to his apartment opened, to cause an explosion and then a fire, prosecutors said.
The manager of The Science Company, Steve Grebe, confirmed the purchase, noting the amount was small and the materials are common in junior high experiments.
The setup in Holmes' apartment had deadly potential, though. Parts of Holmes' carpet were soaked with gasoline and oil and ammonium chloride, a white powder, was poured onto the floor in strips, FBI bomb technician Garrett Gumbinner said.
"It would have ignited and the whole apartment would have exploded or caught fire," Gumbinner said.
He said the system had two other initiating systems. One was a pyrotechnics firing box that would have been triggered by the remote control unit of a toy car left along with a portable stereo set to play loud music. Gumbinner said Holmes told him he hoped the music would lure someone and lead them to play with the car, thereby detonating the explosives.
The other initiating system was a model rocket launch box which operated by means of infrared light, but Holmes told investigators it wasn't armed, Gumbinner said.
The attempt at a distraction speaks to a plan to escape but the traps weren't triggered. Holmes, clad from head to toe in body armor, was found standing by his car outside the theater. He told investigators that the apartment setup was an effort to pull police away from the theater so, under that scenario, he wouldn't expect to see police so quickly.
Police said he volunteered information about the traps. Authorities went to the apartment and carefully dismantled them.