Mental health campaigner Janey Antoniou, photographed in 1999. Antoniou died in 2010 at a hospital in north London.
© Graham Turner/GuardianMental health campaigner Janey Antoniou, photographed in 1999. Antoniou died in 2010 at a hospital in north London.
Anger as hospital's internal inquiry into death of leading schizophrenia campaigner Janey Antoniou not made public

Campaigners are fighting for investigations into the deaths of mental health hospital patients - of which there are on average one a day in England and Wales - to be independent and open to scrutiny.

The move follows an inquest into the death of Janey Antoniou, a leading mental health campaigner who had influenced many organisations including Mind, the Royal College of Psychiatry and Rethink Mental Illness.

Janey, 53, was diagnosed with schizophrenia at the age of 30. She campaigned tirelessly, acting as an advocate for those using mental health services and becoming a trainer with services such as the police. She died in 2010 in her room at Northwick Park hospital in Harrow, London.

The jury at an inquest earlier this month found that her death was inadvertent "following self-harming by use of ligature". While the jury commended staff for trying to "build sincere and trusting relationships" with her, it was highly critical of other issues, including the hospital's risk management.

An investigation was conducted by Central and North West London NHS Foundation Trust, the same trust that had responsibility for Janey's care. Its findings have not been made public. Objections made by her husband, Dr Michael Antoniou, over lack of independence were rejected by the trust. This is now the subject of judicial review proceedings.

There were 3,628 deaths in mental health detention (501 self-inflicted) between 2000 and 2010, accounting for 61% of all deaths in state custody. The proportion of deaths recorded from "natural causes" is also exceptionally high.

Antoniou's judicial review is funded by the Equality and Human Rights Commission. "Anyone detained against their will in an institution is in a very vulnerable situation," said John Wadham, the commission's general counsel. "An independent investigation would ensure that anyone culpable is identified and dealt with, and lessons are learned that could reduce the chances of other people dying."

Since 2004, deaths in police custody have been investigated by the Independent Police Complaints Commission (IPCC), while deaths in prison are investigated by the Prisons and Probation Ombudsman (PPO). In both instances the family is closely involved: a liaison officer is appointed, written updates are provided, and the investigation report and underlying documents are disclosed.

In his judicial review statement, Dr Antoniou says the trust did not keep him informed, interview him or his family, or ask for any input from him. He was told the trust would not be disclosing documents, nor did it offer any support or advice. The experience left him "dazed" and "distressed".

Paul Bowen QC, a barrister at Doughty Street Chambers who appeared for Antoniou at Janey's inquest and has acted for a number of families in similar circumstances, said: "It is plainly not possible for a trust to be, and to be seen to be, 'independent' in investigating a death which may have been caused or contributed to by failures of its own staff or systems."

An article 2 investigation must be initiated by the state, independent, effective, open to public scrutiny, reasonably prompt and involve the family. Deborah Coles, co-director of the charity INQUEST, said: "This is a blatant injustice. Too many deaths of very vulnerable people are not being properly investigated by a number of trusts. They are not being held to account. More rigorous robust and transparent investigations play a critical role in learning lessons to safeguard the lives of others."

A Department of Health spokesman said: "The coroner's inquest is the place where an independent assessment is made of the circumstances of the death of an inpatient."