A 68-year-old man who was critically injured while he tried to stamp out a fire during riots in west London has died, Scotland Yard says.
Richard Bowes suffered head injuries in an attack in Ealing on Monday night and was left in a coma.
A 22-year-old man has been arrested on suspicion of murder.
Police have said four other deaths - a man found shot in a car in Croydon and three men hit by a car in Birmingham - may be linked to the recent disorder.
The 22-year-old was held in west London and has been arrested on suspicion of murder, rioting and burglary.
Mr Bowes, of Haven Green, Ealing, is believed to have been attacked after remonstrating with some teenagers who were setting fire to two industrial bins on Spring Bridge Road.
'Jumped on him'
Police officers were then pelted with missiles as they came to his aid. Detectives have issued an image of a man they identified as a "strong suspect".
A witness, who gave his name as Jim and runs businesses in Ealing, said rioters had attacked Mr Bowes when he tried to put out a fire they had started in a supermarket bin near the Arcadia shopping centre.
Jim, 40, said: "I went up to Spring Bridge Road to check on my other shop and saw him on the ground.
"The rioters had set a bin alight and then they jumped on him when he tried to put it out."
Det Ch Insp John McFarlane said: "This was a brutal incident that resulted in the senseless killing of an innocent man."
Mr McFarlane said the examination of CCTV footage had provided police with a "strong suspect".
"I know that on seeing these images of him people will be able to identify him.
"He had been in close proximity to the attack, recording the events on a mobile device."
Mr Bowes' sister, Anne Wilderspin, 73, from Derbyshire, said: "It was sort of unreal because you don't think anything like that happens to a relative of yours.
"I mean we've been horrified by the reports of the riots and what's been going on.
"It was a shock and it's still a bit unreal in a way."