The Independent can reveal that the shooting had the unintended consequence of exacerbating a cycle of violence that has left at least three people dead over two-and-a-half years.
Mr Hussain's father, Abdi, has now lost two sons to Britain's vicious gang wars. He learnt during the first of two trials of his son's alleged killers that his estranged second son had been arrested for another murder. Five months after Mohammed was gunned down in April 2013, Hussain Hussain fatally stabbed a young fitness instructor in the back. That killing was in Leicester, where Hussain - a known London gang member - moved after being released from prison.
The murder of the fitness coach, Antoin Akpom, followed a confrontation when Hussain and a friend crossed into the victim's territory during a long-running rivalry between gangs in Leicester.
Hussain had claimed self-defence, but was convicted of murder and sentenced to life in jail. He will serve a minimum of 15 years.
"I am satisfied this was yet more offending arising out of postcode rivalry, in which you were steeped," said Judge John Griffith-Williams last month at Stafford Crown Court. "While you were not a member of any Leicester postcode gang, you were more than happy to join in the violence."
Acquaintances of Mr Akpom were accused of seeking their own revenge on the night. But the mob allegedly got the wrong house, killing Shehnila Taufiq, 47, her sons Jamal, 15, and Bilal, 17, and daughter Zainab, 19, who had nothing to do with the feud and died when they were trapped by the flames. Eight men are currently on trial for the family's murder.
Abdi Hussain, a security guard who left the chaos of civil war in Somalia for a new life in Britain, did not go to Stafford in April to see his estranged son convicted. But he has been in court in south-west London for the trial of the man accused of killing his older son, Mohammed. Three others accused of involvement were cleared at a trial last year. At one of their homes, police found a green hooded top printed with "RIP Negus McLean", suggesting a possible motive beyond the long-standing feud between the two gangs.
"They were seven years old when they came here and they grew up in this culture," Abdi Hussain said about this sons. "I was on duty when someone called me, telling me my son [Mohammed] has been shot dead. I regret that they came here. The community is dying; the family is breaking up."
He added: "They saw me as an old-style father, so they didn't listen to me."
Hussain Hussain had long been connected to London's teenage gangland. He had criminal convictions for affray and violent disorder and was questioned over the fatal stabbing of Negus McLean in April 2011.
Negus, who was 15 when he was killed, was the third person to be stabbed in a week amid growing tensions between DA and the Hussain brothers' GMG.
He died at the hands of a "hunting posse" of seven boys on BMX bikes who rode out in search of a victim. They chased Negus who came off his bike and was repeatedly stabbed in the chest and legs.
"It should have stopped with Negus," said his mother, Ingrid Adams. "It was a beautiful Sunday that Negus went out and never came back.
"It's so stupid. There are people out there who think that they're bad ? but they need to grow up. Mums and dads need to wake up.
"If you go to a graveside in a cemetery, do you know how many young people are there? They could have cured Aids; they could have done so many things and they are just dead. We have to forgive. What can you do?"
Four teenagers - all members of the Get Money Gang - were eventually charged with the stabbing of Negus McLean and stood trial in April last year, despite the murder of Mohammed Hussain on the eve of their trial. They were convicted and given life sentences, with one told he would serve a minimum of 19 years.
Attempts were made by the authorities to contact Hussain Hussain and associates of Negus McLean following Mohammed Hussain's murder, to try to end the cycle of violence. But Hussain Hussain had been unwilling to engage. He told his trial that he had inherited a large amount of cash from his brother on his death and had moved to Leicester three weeks before Mr Akpom was killed. Why he moved there remains unclear.
He had contacts in the city through his time at Feltham Young Offenders' Institute. But his father said that police had been involved in the move to get him away from London's gang violence.
Scotland Yard said it was "not prepared to discuss arrangements that may or may not have been made for individuals".
It emerged that Hussain Hussain had been walking down the road with another man when they were confronted by Mr Akpom, 20, a passenger in a car that had been driving past.
Mr Akpom soon left, but came back armed with a dumb-bell and was followed by a group of other people.
Hussain Hussain pulled out his knife - stopping some members of the group in their tracks - and then tussled with Mr Akpom, stabbing him in the back and puncturing a lung.
Hussain Hussain fled to London that night by taxi. He packed up a parcel containing several thousand pounds, according to a driver, and tried to take a flight to Amsterdam or Marrakech.
However, as a refugee from Somalia, he needed a visa. Instead he took a taxi to Cardiff where he was arrested.
The parents of the murder victims have not met, but they share bewilderment and grief at what happened to their families and how it changed all of their lives.
"I never realised it would continue like this," said Mrs Adams. "I don't even know what has gone on, to be honest. If it was revenge, it would have been straight away, not two years after.
"I feel sorry for that man. He lost two sons and that's really sad."
- The Independent
