Psychiatric hospitals have a duty to keep their patients safe, which means taking extra care with patients suffering acute depression who may be at risk of self-harm.

So campaigners argue that when a patient commits suicide, it is vital that a thorough investigation should discover any failings by doctors and nurses and any weaknesses in hospital systems of communication or levels of staffing.

But, unlike deaths in prison or police custody, fatalities in psychiatric units are not reviewed from the start by a fully independent investigator. Initial reports are usually prepared by staff of the NHS and kept confidential to the health officials and family concerned. Only at the subsequent inquest does an independent inquiry take over.

Critics call this 'a recipe for cover-up by the NHS'.

File on 4 reports on a series of suicides in one psychiatric unit which have led the local coroner to accuse the NHS of 'a catalogue of failures stemming from an institutional complacency'.

Reporter - Gerry Northam