My first reaction as well.. This isn’t chump change. Investigators should spend more time on his financing than his Internet purchases. He spends $15k to shoot people in a movie theater? I want to know why the cops refrained from going to his apartment earlier that night to tell him to turn down his loud techno music.. There were complaints phoned in.
I think the answer to your question is all the cops were at the theater by then. A loud music call would be a no priority at that point.
All first responders went to the theater. Loud music, traffic accidents, dogs barking, etc... None of that mattered after the first calls from the theater.
Knew it was boobytrapped...?