The overall murder rate in England and Wales is low compared to other countries and people with mental-health problems only commit a small percentage of them. There has been no research into the kinds of murder committed by people with mental-health problems in England and Wales so researchers from the University of Manchester analysed 3,930 murders committed between 1997 and 2003. The use of firearms was rare and in 36% of cases a sharp instrument was used. Murderers with schizophrenia tended to use a sharp instrument and predominantly killed a family member or spouse in the home. Murderers diagnosed with an affective disorder were more likely to use strangulation or suffocation while alcoholics used hitting or kicking more often, mainly to kill acquaintances. Drug-dependent murderers were more likely to use 'non-violent' methods such as poisoning.
Rodway, Cathryn ... [et al] - Methods of homicide in England and Wales: a comparison by diagnostic group Journal of Forensic Psychiatry and Psychology April 2009, 20(2), 286-305