Three years after the schizophrenic Christopher Clunis killed Jonathan Zito, a dramatisation of the story is helping doctors and social workers to learn from the tragedy. Bridget Freer reports
It is a rainy December afternoon in Uxbridge. Lead grey skies and a light drizzle do not show the already unprepossessing bulk of the Hillingdon Hospital staff social club in a good light. Inside, chairs and tables have been pushed aside. The stage is set for a joint training session organised by the London Borough of Hillingdon Social Services and Hillingdon Health Agency, though "training session" is a dry description for the radical piece of theatre that will follow.

Assorted doctors, police, social workers and nurses have been gathered together to watch a play that traces in vivid detail the descent of a man into mental illness, to the point where he carries out a brutal and random murder.

The roots of this performance lie in a similarly grey December day in 1992. At about 3.15pm on 17 December, at Finsbury Park Underground station in north London, 27-year-old Jonathan Zito was stabbed to death by Christopher Clunis, a diagnosed paranoid schizophrenic.

Three years later that tragic event and its causes are still being debated furiously. Partly because the nightmare keeps recurring - official figures suggest that one person a month is killed by someone who has recently been in psychiatric care - and partly because the Zito/Clunis case itself is back in the news. Only last week, Christopher Clunis's solicitor launched a High Court action against Camden and Islington Health Authority for "failure to care". Clunis, who is thought to be seeking damages in excess of pounds 50,000, is claiming that he was not given adequate care by Friern Hospital and that its negligence led to his being convicted of manslaughter on grounds of diminished responsibility, for which he was sent indefinitely to Rampton top security hospital.

Jonathan Zito's widow, Jayne, has been instrumental in keeping alive the debate about whether potentially dangerous patients should be released into the community. On hearing that Clunis was suing for damages she said: "I don't believe he should benefit from my husband's death". She has now issued a civil writ against Christopher Clunis for criminal assault - this is the only legal option open to her; she cannot sue the health authority, because, as her solicitor, Sally Moore, explains, "The health authorities had no duty of care to Jayne or her husband, Jon, but they did have a legal responsibility for the care of Christopher Clunis".

Soon after her husband died, Jayne Zito - who had had first-hand knowledge of the mental health services, having worked as deputy manager of a rehabilitation unit for the mentally ill - declared that Jonathan's death had been both predictable and avoidable. At Christopher Clunis's trial, in the summer of 1993, she called for a public inquiry. This eventually got a response from the then health minister, Virginia Bottomley, and an inquiry by Jean Ritchie QC was commissioned.

The Ritchie report was published in February 1994. As is normal after such inquiries, it was bought by all the health and social service authorities in the land and distributed to their senior executives to assimilate and learn from. Unusually, it did not end up stuffed in the collective "pending" tray, to fade from the collective memory. Diane Desmulie, then director of commissioning with the Barking and Havering Family Health Services Authority (FHSA), read the Ritchie findings from cover to cover. "It was a landmark report and I felt very strongly that its lessons should be absorbed into the NHS," she says.

She was aware, however, that although she had found Ritchie's investigations compulsive reading, it might be too much to expect all the GPs in her area to plough through it. She realised she would have to find another way to grab their attention. "I found the Clunis report as gripping as any novel, and I realised it had dramatic properties. People learn a lot from case histories and I realised that this was just one big case history in which all the difficulties and all the failings were laid out very clearly."

Desmulie approached Studio 3 Arts, a group based in Barking who work on art, theatre and video projects with local people. Kathryn Gilfoy, a producer with Studio 3, began researching the project and, after the go-ahead from Desmulie, commissioned a scriptwriter, Julie Garton, to turn the Ritchie report into a play. It was a gargantuan task: the report is 140 A4 pages of precise detail, which takes approximately seven hours to read; the resulting play, Through The Net, is 50 minutes long.

But Desmulie's instinct paid off handsomely. Having seen a preliminary run-through of the play, her job-sharing chief executives were so impressed that they wrote to every chief executive or director of a health service agency in the London area urging them to use Through The Net as part of their staff training.

More importantly, they realised they couldn't just keep it to themselves. The key message of the Ritchie report is that if the social and health services had told each other what was going on, disaster could have been averted. "When there are blockages of communication where agencies work together, you need to find imaginative ways round them," says Desmulie. "This was such an opportunity and so social services were invited in on the act, too."

Back in the Hillingdon Hospital staff social club, the audience are instructed to put their chairs in a large circle with access for the actors at each corner. Alan Cooke, who plays Christopher Clunis, walks to the centre and plays a haunting saxophone solo - before his illness Clunis worked as a professional musician, something he had in common with Jonathan Zito. The other three actors - Clare Perkins, Nirjay Mahindru and Joanna Carrick, who between them take on 20 other roles - gather around, here playing Clunis's close and loving family.

From the very first you are gripped. Here we have not a monster with a knife, not a nut, not merely a case or a problem, but a real person, and for the next 50 minutes you witness the slow disintegration of his personality. Watching it is an incredibly powerful experience, not least because of the strength of Cooke's portrayal. The fact that you know exactly how it all turns out does nothing to dull the power of the drama.

One of the most extraordinary things about watching Through The Net is that the rest of the audience are watching themselves. The assembled doctors, police officers, social workers, psychiatric nurses, community psychiatric nurses, purchasing directors and probation officers watch an increasingly ill, desperate and violent Clunis spinning through what doctors call the "revolving door", a sequence of events that keeps repeating: a breakdown or crisis, into hospital, medication, symptoms disappear, out of hospital, stop medication because of side effects and lack of supervision, symptoms return, family or police intervene, back into hospital.

For the watching professionals the incidents shown are commonplace occurrences. There is the occasional shake of the head or nod of recognition as one of the protagonists appears and steers Clunis back into the revolving door. The revelatory thing about Through The Net is that whereas in real life Clunis would have walked into their professional world and exited at the limits of that world, here they are able to see the whole picture. "They tend to deal with people from their own perspective and look at the boundaries of their own jobs," Desmulie says. "Through The Net puts Clunis in the centre."

The play itself is the centre, but not the whole, of the training session, which starts with a video compilation of the lives, thoughts and views of a group of schizophrenics who haven't fallen through the net, and finishes with the audience breaking up into groups for an hour-long discussion of the issues raised.

Reactions to the play, the afternoon I went to see it, were very strong: people spoke of having been "moved", "shaken up", "angry" and "disturbed". One senior social worker who had seen a previous morning performance had come away saying, "Maybe I have done some of those things." He had spent the whole of the rest of the day going through experiences of his own to see if he might, at any point, have allowed a Clunis into the community where he posed a threat to himself and others.

Jayne Zito now co-runs the Zito Trust, a registered charity that supports victims of community care and campaigns for a better provision of care for the severely mentally ill. Although both the trust and the Ritchie recommendations highlight the catalogue of errors committed by NHS and social services staff, they both point out that, on the whole, they are doing their best in difficult, drastically under-resourced circumstances and that the ultimate blame for the failure of care in the community lies in the lack of resources. Jayne Zito says: "Our message is: we know there's a resource problem but, by God, do your job to the best of your ability, that's all we're asking of you."