Zahid Mubarek shared a cell with Stewart for six weeks

The Law Lords ruled on Thursday that Home Secretary David Blunkett was wrong in refusing to order an inquiry into Zahid Mubarek's death.

The 19-year-old's family took their case to the House of Lords, which was the latest step in their campaign for a new investigation into the killing at Feltham Young Offenders' Institution in west London.

They want to know why the first-time offender, who was sentenced to three months for theft, shared a cell with violent criminal Robert Stewart.

Stewart, who was later diagnosed as a psychopath, wrote racist letters to friends and hung a Ku Klux Klan sign on his cell notice board.

This case is a wake-up call for the prison service just as the Lawrence murder was a wake-up call for the police Family solicitor Imran Khan The murder of Zahid Mubarek

He bludgeoned Mubarek to death in March 2000 - the day he was due to be released.

A High Court judge ruled in September 2001 that Mr Blunkett was wrong to refuse to sanction a public inquiry into the killing.

He said an investigation should be held under Article 2 of the European Convention on Human Rights.

But the ruling was overturned by the Court of Appeal in March 2002, after judges said it had been established the Prison Service was at fault, an inquiry had been held and Stewart convicted of murder.

They said there was no basis for prosecuting any member of the Prison Service.

Robert Stewart had a Ku Klux Klan sign in the cell

But on Thursday Lord Bingham, sitting with Lords Slynn, Steyn, Hope and Hutton, said he did not accept the argument from the home secretary that a further inquiry was unlikely to unearth new and significant facts.

They ruled that the state was under a particular duty, not only to ensure that a prisoner's right to life was protected, but also to publicly investigate the death of an inmate due to prison system failures.

"Those who have lost their relative may at least have the satisfaction of knowing that lessons learned from his death may save the lives of others," said Lord Bingham.

Zahid's uncle, Imtiaz Amin, told BBC News: "We are overjoyed.

Torrid time

"It has been a torrid time for the family.

"It has been a long three years with lots of ups and downs but we are happy that we have got a decision in our favour for a change."

Suresh Grover, family advisor, said: "It is a historic day for the family who have been campaigning for over three years for a public inquiry into the circumstances that led to Zahid's brutal and racist murder.

"This could have ended earlier but the home secretary has dragged his feet.

Public confidence

"He could have ordered an inquiry in October 2001 when Justice Hooper said there should be one.

"The inquiry must be open, accountable and transparent and the family must have the right to agree on the terms of reference where by we can learn the real lessons of the murder of Zahid Mubarek and we can insure that the public has confidence that such a murder will never take place again."

Imran Khan, the family's solicitor said: "This case is a wake-up call for the prison service just as the Lawrence murder was a wake-up call for the police.

"The family is entitled to know why the prison service failed Zahid."

Fault accepted

Mark Leech, editor of the Prisons Handbook, an annual guide to the penal system, said: "The reality in our overcrowded prison system, and particularly at places like Feltham, is that these events could happen again."

The Home Office's Commissioner for Correctional Services, Martin Narey, said: "We are obviously a little disappointed.

"The Prison Service has been involved in two inquiries including an internal inquiry which produced a very critical report, and then a very extensive investigation by the Commission for Racial Equality, which also produced a highly critical report.

"We thought that was an end to the matter, but if there has to be another inquiry, the Prison Service will offer its full co-operation again.

"I don't think there's anything new to discover and from the outset we have been very frank in acknowledging that this was our fault."