More than £80m has been 'wasted' on inquiries into murders and manslaughters by mental health patients, a leading charity has claimed following an exclusive investigation.

Failings identified by independent inquiries into the care of these patients regularly take up to five years to put right, the investigation revealed last week.

Marjorie Wallace, chief executive of Sane, which campaigns for people affected by mental illness, said this means that millions of pounds have been wasted on a system that is failing to protect patients or the public.

'The money's wasted because whenever you go back to trusts, the recommendations haven't made much difference or been carried out,' she told HSJ.

The most complex investigations can cost more than£250,000, Ms Wallace said, taking the total cost of investigations since their statutory introduction in 1994 to around£80m.

Trusts should be required to prove to inspection teams that they have fulfilled inquiry recommendations within three to six months after an incident has taken place, she added.

Currently, strategic health authorities must commission an independent investigation every time a person who has used mental health services in the past six months kills someone.

Trusts draw up action plans to tackle any recommendations and are monitored by SHAs until they have carried out all of the recommended actions. found there were 27 outstanding cases where inquiry recommendations related to incidents dating back to 1996 were yet to be implemented.

Ms Wallace said the figures would be in the hundreds if the six-month cut-off point was extended to include people who previously used services but had 'slipped through the net'.

She called for action to be taken immediately, as opposed to after a court conviction, which is usually the first point at which independent investigations commence.

In the past, this has meant that independent investigations have taken up to four years to publish, pending legal appeals.

In the most notorious case in HSJ's investigation, Kent and Medway Partnership trust was found to still be working on problems identified after Michael Stone's hammer attack on a mother and her two daughters in Kent in 1996.

This is because Stone appealed his sentence twice and launched a judicial review against the independent report being published on the grounds it would infringe his right to privacy.

Many have complained the official guidelines are too vague on whether SHAs can commission independent investigations before a court verdict has been reached.

A Department of Health spokesman said the advice contained in a memorandum of understanding from November 2006, which refers to 'local investigations' also applies to independent investigations set up by SHAs.

It says: 'Where police or other legal investigations are ongoing, the timing for these processes should be agreed with the local police or Crown Prosecution Service.'