Who is Norman Renner from Chasing the Dime: A Novel and what is their importance?

Norman Renner is theb detective assigned when Henry calls the police after discovering the bloody mattress in Lilly Quinlan's apartment, Renner is methodical and thorough. He takes Henry's statement, one sentence at a time, and slowly picks it apart, looking for the reason that Henry has become so involved with a hooker he claims to have no prior knowledge of.