Question

Mary murdered her boyfriend, bob, and then fled across state lines to avoid arrest. at her trial, may claimed that she was already in the neighboring state when bob met his untimely demise. on the other hand, the burden of proof for an affirmative defense rests with

Answer 1

I believe the answer is: The police/justice department

affirmative defence refers to the factual evidence in the crime scene that might support or discredit the accusation made by the plaintiff.
This type of evidence usually obtained through the forensic team which is a part of the police/justice department.