This paper analyses people charged with homicide offences committed during the acute phase of mental illness. High rates of drug misuse, especially of drugs known to induce psychotic illness and brain injury, were reported. Evolving auditory hallucinations and delusional beliefs that led the person to believe they were in danger were the symptoms strongly associated with lethal assault. The victims were mostly family members or close associates. Only nine of the victims were strangers, including three fellow patients. Most lethal assaults (69%) occurred during the first year of illness, and the first episode of psychotic illness was found to carry the greatest risk of committing homicide.