Daniel Gonzalez, charged with stabbing two men and two women to death in September 2004, allegedly suffered from hallucinatory voices that commanded him to kill, the Telegraph newspaper said.
Dr Edward Petch, Broadmoor hospital's psychiatric consultant, told the London criminal court, The Old Bailey, "I have never seen anyone bite himself with that ferocity. A number of staff described it as a clear attempt to die."
Prosecutors contend Gonzalez wanted to be a famous serial killer by killing at least 10 people.
The defense concedes Gonzalez killed the four victims, but contends he was suffering from auditory hallucination that diminished his mental capacity. The defense contends he is guilty of manslaughter, not murder, the Telegraph said.