By Dominic Casciani
Community affairs reporter, BBC News website
There is one simple question which lies unanswered at the heart of the fatal attack on Zahid Mubarek in Feltham Young Offenders' Institution at 3.35am on Tuesday 21 March 2000: Why was he sharing a cell with Robert Stewart when there was information within the Prison Service that Stewart was a violent and sometimes racist psychopath?
Robert Stewart's message on a cell wall after the murder
The unprecedented decision by the Law Lords to order former Home Secretary David Blunkett to hold a public inquiry into the murder was a huge victory for the dead teenager's family.
But after a year of hearings, will the family be any nearer to the truth? The inquiry has looked deep into questions of racism in prisons, the widely-reported shambolic crisis-management nature of Feltham in 2000 and the individual motivations of both ordinary officers and governors.
But beyond the stark headlines and horrific detail, the picture that emerged during the hearings was incredibly complex and the Mubarek family have been looking to Mr Justice Keith to give them some quite simple answers.
As the inquiry is published these are the key questions:
Was the teenager's placement in that cell, accidental, negligent or, worse still, deliberate?
Was the killing pre-meditated or a seemingly random violent urge? Was it brought on by Stewart's mentally disturbed state or by his self-confessed racism?
Would Mr Mubarek have been alive today if he had been white, as Britain's race watchdog Trevor Phillips has argued.
The inquiry has heard extraordinary allegations and terrible detail of an institution that, by the admission of a great deal of people who were there, had been imploding rather than offering any chance of reform to its deeply troubled population.
While the annual cost of locking up a teenager at Feltham was higher than the fees to send a boy to Eton, it appeared, in the minds of many observers, to be doing little to turn around broken, damaged lives.
And it was into this institution, very publicly damned by the then chief inspector of prisons, that first-time offender and heroin user Zahid Mubarek was marched.
Excluded from school at 15, Mr Mubarek got into drugs and started to slide into criminality.
Arrested for stealing razors worth £6 and interfering with a motor vehicle, he may have escaped jail had he not failed to follow Probation Service orders to tackle his drug problems.
But fail he did, and Waltham Forest magistrates, in east London, concluded they had no other option than a three-month jail sentence.
Mr Mubarek was already inside Feltham when Stewart, also 19 at the time, was transferred to the jail.
Stewart, from near Manchester, had spent most of the previous three years in custody.
He had 19 separate convictions for 73 offences, including one for actual bodily harm and several assaults and was facing more charges related to sending intimidating letters.
Evidence presented at the later murder trial revealed Stewart to be seriously disturbed.
His security file was one of the biggest ever seen by one senior officer who appeared before the inquiry.
On 8 February 2000 he was allocated a double cell with the soon-to-be-released Mr Mubarek as Feltham faced over-crowding problems.
Six weeks later Mr Mubarek was dead.
Following his death, some of the other inmates described Stewart's behaviour at Feltham as "strange, weird and aggressive" - and there was no indication that he had made any friends.
According to the Commission for Racial Equality's report on the murder, one prisoner said of Stewart: "I called him Madman. Other prisoners had names for him like Sicko.
"We called him names like this because you must be mad or sick to tattoo RIP on your forehead.
"If he used to lose [at table tennis] he would smash his bat on the table. He was aggressive. He would sit and stare at people. I have had him stare right into my eyes.
"When I've asked him what he's looking at, he would reply 'nothing', it was crazy."
Two nights before the murder, Stewart watched Romper Stomper, a grim and intense Australian film, starring Russell Crowe, about a racist gang that attacked Vietnamese refugees with wooden clubs.
In letters written hours before the killing, Stewart fantasised that he was the gang leader.
"Did you watch Romper Stomper? It's mad. I watched it in Altcourse, I'm in it HA HA, wish them skinheads was in ere, nig nog would soon shut up I think.
"Am gonna make me own beer in me pad, watch some tv + tump [thump] up some jigaboos.
"Gonna nail bomb Bradford, Moss Side - all the non-white areas."
Mr Mubarek, who was trying to sleep ahead of his release the following morning, complained the cell was too bright.
Stewart eventually responded and threw a pair of his own underpants over the cell lamp.
At 3.35am on the morning of 21 March, Stewart took a table leg he had already separated from the table and began battering his cellmate over the head.
He hit Mr Mubarek between seven and 11 times. Stewart then pressed the alarm and waited for the prison officers.
After initially being left with Mr Mubarek, Stewart was moved to a nearby cell where he washed his blood-stained hands and clothes.
Meanwhile Mr Mubarek was on his way to Charing Cross Hospital, in west London, where he did not recover from his injuries.
Back at Feltham, Stewart took the heel of his rubber shoe and began scratching a message on the wall.
"Manchester just killed me padmate. Swastika RIP OV M1CR."