Three people arrested over the murder of a street cleaner who was stabbed to death as he tried to stop a burglar have been released on bail, police said.
Piotr Mikewicz, 40, was attacked on Wednesday afternoon in Rylett Road, Shepherds Bush, west London, and was taken to hospital by air ambulance but died the next day.
Scotland Yard said six people were arrested in connection with Mr Mikewicz's death on Thursday.
A 30-year-old man who was arrested on suspicion of murder remains in custody at a central London police station.
Two other men and three women were all detained on suspicion of assisting an offender, with the two men and one of the women having now been bailed pending further inquiries.
Police are continuing to appeal for witnesses to the attack, while tributes have been paid to Polish national Mr Mikewicz, who was described as "a friend to everyone with a colourful and friendly personality" by his employer, private contractor Serco.
Deputy leader of Hammersmith and Fulham Council Greg Smith said Mr Mikewicz had "courageously tried to intervene" when he saw a crime being committed.
He added: "Everyone at the council is deeply saddened by the tragic news that Piotr Mikewicz, who was one of the borough's dedicated street cleaners, has died after being stabbed by some scum of the earth who obviously has no regard for human life.
"Piotr was a hard-working man who was a friendly face to all who knew him on his regular beat.
"Piotr was a family man who courageously tried to intervene when he spotted a crime in progress, and our thoughts are with his family and friends at this extremely difficult time.
"Although this is an isolated incident, it is deeply shocking that Piotr's genuine act of bravery should end in such brutal violence and we trust that the perpetrators of this evil will be brought to justice swiftly."
Richard Cassell, a lawyer who owns the house that was burgled, told the Evening Standard he was "devastated" by the death.
He said: "I didn't really know Piotr because he usually comes round when we're at work, but many of our neighbours knew him and talked to him. He was a regular and a part of the neighbourhood.
"We would like to try and get in touch with his next of kin to express our gratitude.
"The most tragic and ridiculous thing is that all they took was one laptop. It's not valuable at all, it's an old Dell of mine. They also tried to take my wife's Mac but dropped it and it smashed.
"To kill a man for something like that is so sad, so pathetic."
Mike Boult, director of Serco, said: "He was a unique and special person and he will be sorely missed, but our loss is nothing compared to that of his family and friends. They are in our thoughts and, on behalf of everyone at Serco, I want to send them our sincerest sympathies and condolences. We will do everything we can to support them at this very difficult time.
"Piotr was a popular member of Serco's close-knit environmental services team, not only because of his hard-working nature but because he was a friend to everyone with a colourful and friendly personality.
"Anyone who knew Piotr knew he was a truly good and honest person. He had a strong sense of what was right and wrong. He wasn't just a road sweeper, he was a part of the community he worked within, genuinely caring about the residents and his 'beat'."
Acting Chief Superintendent Peter Clilverd said in an internet blog that police are using "all of our available resources" to catch the killer.
Police said they did not yet have the result of a post-mortem examination, which was due to be carried out yesterday.
The local authority has opened a book of condolence and is flying the flag at Hammersmith Town Hall at half mast.Reuse content