Detectives are appealing for information after a man assaulted in Greenford died from his injuries.
He was attacked in the Whitton Avenue West area of Greenford at around 4.30pm on Friday.
He remained critically ill in a west London hospital until his death on Sunday.
Police are awaiting a formal identification but say the victim is believed to be Grezgorz Fiuk who was aged 47 and lived in Greenford.
His family have been informed and a post-mortem examination will be held in due course.
A police statement said: “Three people have been arrested in connection with the investigation. One was subsequently de-arrested, one released on bail to a date in July and one released under investigation.
“The parties are believed to be known to each other and officers are not looking for anyone else in connection with the incident.”
Any witnesses who are yet to speak with police and anyone with information are asked to call 101, ref 8115/10jun.
To remain anonymous contact Crimestoppers on 0800 555 111.