In 1997, a forensic examiner in Berlin reported one of his more unusual cases in the journal Forensic Science International. A 31-year-old man had retired for the evening to the converted garden shed behind his mother’s house, where he lived with his German shepherd. Around 8:15 p.m., neighbors heard a gunshot from the direction of the shed.

Forty-five minutes later, the man’s mother and neighbors found him dead of a gunshot wound to the mouth, a Walther pistol under his hands and a farewell note on a table. Most of his face and neck were gone—and there were tooth marks around the edges of the wounds. A half-full bowl of dog food sat on the floor.

The German shepherd was calm and