89 year old Man Bites and Dies

This is another strange case. An 89 year old man from Ikeda City, Osaka, was arrested for biting a 49 year old woman in a nature park in Kawanishi City, Hyogo. 

Two police officers attempted to escort the man to a police car, but he sat down on the ground and refused to move. The police officers put him on a stretcher borrowed from the park management office and carried him to the police car, about 200 meters away. The police officers said his face was pale and he appeared semiconscious after being put in the police car, so they drove him to the hospital where he died about 90 minutes later. 

An autopsy is being conducted to determine the cause of death. What happened here? I will probably never find out.