Background. Mental disorders are major risk factors for suicide. Not all those who suffer from mental disorders kill themselves. Additional information is required to differentiate higher and lesser risk patients.

Methods. Retrospective case–control comparison was made of cases of suicide/undetermined death with living controls using psychological autopsy in South East Scotland. Cases and controls were matched for age, sex and mental disorder. Informants were those closest to cases and controls. The subjects were 45 cases of suicide/undetermined death and 40 living controls.

Results. Cases and controls did not differ significantly in severity of mental disorder. The main factors independently associated with undetermined death or suicide were: a history of deliberate self-harm (adjusted OR 4·1); physical ill health (adjusted OR 7·8); and engagement by mental health services (adjusted OR 0·01). Other antecedents associated with increased risk (criminal record, police involvement, financial problems and failure to vote) and those associated with decreased risk (contact with a doctor and in-patient care) did not exert effects after controlling for confounding.

Conclusions. Controls were receiving more care of whatever kind. Treatment of mental disorder co-morbid with physical illness and a history of deliberate self-harm may be especially important. Factors that separate those with mental disorder at high risk from those at lesser risk relate to care levels provided, which may be a function of engagement by and with health services. The role of mental health professionals is beneficial in suicide prevention. The focusing of that role towards engaging alienated or ‘difficult’ patients should be addressed.