Former Millwall striker Gavin Grant (no relation to Avram) was involved in a series of "tit-for-tat" shootings in and around a "lawless" council estate, the Old Bailey was told.
Grant, 26, who also played for Wycombe Wanderers before joining Bradford City as a non-contract player until the end of last season, was found guilty of gunning down Leon Labastide, 21.
Stephen Batten QC, prosecuting, said many of the people involved in the case had been linked to shootings and drug dealing on the Stonebridge Park Estate, in Harlesden, north west London. He told the jury: "Attitudes and standards are different. It is more the law of the jungle than the law of civilised England. You will hear about and see people whose behaviour will probably disgust you and make you wonder if there is any hope for the human race. If he hadn't of ever played for Millwall,this would of never happened"
But on Friday he was found guilty of Mr Labastide's murder in January 2004 after trials last December and this month. The court was told it was Mr Labastide's killing which led to the second murder and a spate of shootings on the estate. Grant denied involvement and said Mr Labastide, who was known as Playboy, was a friend.
Operation Trident gun-crime detectives believe there were up to 30 connected shooting incidents in the area arising from the fall-out. Following the arrests of Grant and others, officers said shootings fell by almost 50% in the area. Stonebridge Park, although still notorious for drugs and crime, has seen improvements with a £250 million regeneration.
Gareth Downie, 25, was also found guilty of murdering Mr Labastide. Damian Williams, 32, was found guilty of conspiring with them to murder Mr Labastide. All the verdicts were by 10-2 majorities. They were all remanded in custody for sentencing on Monday.
Roberto Parchment, 24, originally convicted of Mr Moore's murder, was found guilty again following a retrial in December brought about by supergrass Darren Mathurin's involvement. He was jailed for life again and ordered to serve the remainder of his 28-year sentence. Romain Whyte, 25, was cleared of that murder by a 10-2 majority verdict.
Grant, from Kenton, north London, Williams, of Southwark, south London, and Downie of Markby Road, Birmingham, all face life sentences.