 In each scene with Detective Donald Kimble (Willem Defoe), Mary  Harron asked Defoe to portray his character three different ways: 1)  Kimble knew Patrick Bateman killed Paul Allen, 2) Kimble didnt know  Bateman killed Allen, and 3) Kimble wasnt sure if Bateman killed  Allen. Harron would then edit the takes together, giving the  audience an unsure vibe of what Detective Kimble thought of Bateman.