Massacre suspect's neighbor: 'I'm counting my lucky stars'

Aurora, Colorado (CNN) -- Kaitlyn Fonzi put her hand on the doorknob of the apartment upstairs from hers around midnight Thursday, irritated by the blaring electronic music inside. The upstairs neighbor didn't answer when she called through the door. He'd cranked up the stereo, the deep bass of the music reverberating through the floor into the apartment Fonzi shared with her boyfriend. The door felt unlocked, but Fonzi decided not to open it. "I yelled out and told him I was going to call the cops and went back to my apartment," she told CNN. It's a move for which Fonzi said Saturday she's "counting my lucky stars." "It makes me feel extremely grateful, and it's definitely made me thank God, too, and thank just my instinct," Fonzi said. Behind that door, investigators say, was a tripwire that would have touched off an array explosives and flammable liquids in the home of Colorado massacre suspect James E. Holmes. Anyone who crossed that threshold "would have sustained significant injuries or lost their life," Jim Yacone, the head of the FBI's Denver office, told reporters Saturday afternoon.