Bed of Deceit

A retired police officer is discovered in his bed, dead of a single gunshot wound to the head. His wife first says the motive was robbery; then she tells police he committed suicide. It would take careful examination of the evidence at the crime scene, the tape from a bank surveillance camera, and forensic textbooks found in the victim's home to write the final chapter of this real-life whodunit. [also marked as S8:E19]