Originally posted by siriuswriter
I think the official explanation is that he wasn't taking his medication - and so the thoughts inside his head became full-on delusions and hallucinations. When he calls his lawyer from the payphone, you can see him downing a mouthful of pills.Also, the scene where the detective goes to see Bateman for the second time, they actually did three takes - one with Willem Dafoe acting as if he knew Bateman was innocent, one where Willem Dafoe knew Bateman was guilty, and a last one where Willem Dafoe acted as if he was covering a regular suspect. Then they edited all of them together.
No, the official explanation from the director, the screenwriter and the author of the book was that Bateman DID kill all those people, but everyone around him were all too coked out/drunk/self-absorbed/stupid to care. Take the scene where he goes back to the apartment. The more or less official explanation is that the apartment owner found Paul's body and quietly disposed of it without alerting the cops because that would decrease the chance that she'd be able to sell it again.
The detective scenes are irrelevant to the story.