>>213520360
>>213520215
Though arguable he never murdered anyone.
The novel infers that
>He killed a man that just looked like Paul Allen and in his delusion actually believed he killed Paul Allen, hints his confusion over the entire situation
>The prostitute with the rat in the anus
Everything else is either daydream fantasy, unreliable narration from him, or just didn't happen.

Also for the record
This isn't even Paul Allen's apartment in the movie. Supporting the theory.
As he literally walked into a random dudes apartment and put a random message on the messaging saying saying "This is Paul Allen blah blah blah."