The brother of a former boxing champion who was killed at a nightclub has urged witnesses to come forward.
James Oyebola asked customers to stop smoking
James Oyebola, 47, was shot dead in Chateau 6 in Fulham Road, south-west London, on 23 July after asking customers to put out their cigarettes.
He died in hospital on 27 July after his life support was turned off. Three men have been held; one was bailed.
"There are people out there who know who shot my brother," Kelly Oyebola told BBC Radio 4's Today programme.
"There's no question about that... as there are people out there who witnessed other murders.
"What we really need to do is to unite and come forward with this information."
Mr Oyebola, a former probation officer who now runs a youth mentoring scheme in south London, urged anyone with information to come forward.
"It is when people start rising up and giving information then certain criminals suddenly realise it doesn't take much for people to come forward," he said.
"That may be one way in which we can curb this very devastating crime."
Three people have been arrested as part of the murder inquiry.
One of the suspects - a 19-year-old man - was detained at Gatwick Airport on 1 August. He has been released on bail and is due to return in mid-August.
A 22-year-old man, who was arrested on Tuesday in Putney, south-west London, was still being questioned.