Events of L.A. Noire
Officer Mathiason is encountered during the Street Crime "Vengeful Ex", where Officer Mathiason attempts to calm Morgan Boehringer, an elderly man who is armed with a revolver and physically abusing his ex-girlfriend, Joanna Alford. When Officer Mathiason reaches for his own pistol, Boehringer shoots and kills the Officer instantly. Cole Phelps and Rusty Galloway killed or possibly wounded Boehringer in a shootout moments later.
- Morgan Boehringer's ex-girlfriend, Joanna Alford, was also injured when Boehringer ran across a nearby street - after killing Officer Mathiason - Boehringer kills the driver of a large truck causing it to strike Miss Alford.