MILAN (AP) — Italian authorities are trying to unravel the mystery of an actor who was strangled on a theater stage in Pisa during a hanging scene.

Pisa University Hospital says doctors declared 27-year-old Raphael Schumacher dead late Thursday, five days after the incident. Italian news reports said a recent medical school graduate in the audience sounded the alarm after noticing the actor was under distress while enacting a hanging.

The daily il Giornale quoted the directors as saying the piece, about an adolescent's existential crisis, was supposed to end with a fake pistol shot, but that Schumacher changed it without informing them.

The news agency ANSA reported Friday that prosecutors are investigating whether a lapse in safety procedure was to blame, with the focus on a possible stage accident rather than suicide.