A nightclub promoter was executed in the street because his drug dealing friends were muscling in on someone else's patch, police said today.
Daniel Herbert, 27, was beaten unconscious by a gang of men and then shot in the head in Bermondsey, south east London, on August 17 last year.
Investigators revealed he was "singled out by association" in a territorial dispute among gangs selling drugs to the capital's lucrative nightlife trade.
His mother Ann visited the scene of his murder for the first time today to appeal for information as police asked for help to break down a wall of silence around the shooting.
Speaking in Clements Road, Mrs Herbert, 47, of Orpington, Kent, said her son's bedroom remains untouched since he walked out of the door one year ago.
She said: "It doesn't get any easier, Daniel was my only child, he was my every day. When you have only got one you focus on him. The days are empty and quiet.
"I am waiting for the phone call to say they've been arrested, but it is not going to bring him back. I'm sure a lot of his friends know something.
"But they haven't spoken to police. It's the Bermondsey mentality, do not speak to the police, even when your friend has been murdered. They are probably scared too.
"I just know who I am and I know who Daniel was, and people have got to do the right thing. How can you live with that? How can a human do that to another?
"How can you cover up or know your friend has been involved in a murder and not say anything? That is why I find it really hard. It's killing me.
"I do not understand how anyone could even want to be associated with someone who has killed someone, or their family.
"Daniel is never going to come back. I don't believe people think that he has actually gone."
Detectives are hunting up to five white men seen chasing Mr Herbert through several streets as he banged on the windows of passing cars pleading for help.
He was cornered at the junction of St James's Road and Clements Road where his mother believes he "ran out of puff" because he suffered from asthma.
Mr Herbert was beaten unconscious, pulled to his knees and shot in the head with a converted pistol that has not been recovered. He died in hospital.
The victim had been visiting friends in Bermondsey, where he grew up. His family suspect he may have been drawn towards petty criminals by a friend who moved to Orpington.
Detective Inspector Richard Beadle said investigators need information to take them "a little step further" and to bring a case to court.
He said: "Daniel was attacked as some form of retribution. He was in the wrong place at the wrong time and has been singled out by his association with others.
"There is a link to low-level drugs within this area. Daniel himself, in the lead up to his murder, has been on the periphery of this.
"There are other people who are directly involved, and I can categorically say he was singled out by association on that particular night.
"That in any circumstances is sad, but it's unfortunate he found himself alone and facing the wrath of this group of people for somebody else's actions."
Detectives believe they know the identity of the killers and have questioned eleven suspects. Nine people, aged between 20 and 28, remain on bail.
* Anyone with information is asked to call the incident room on 0208 721 4961 or Crimestoppers on 0800 555111.