Detectives are appealing for information and witnesses following a murder in Hounslow.
Police were called to Montague Road, Hounslow, TW3 at 02:52hrs on Sunday, 8 October following reports of an altercation.
Officers and London Ambulance Service found a man in his 30s collapsed in the alleyway between Lampton Road and Montague Road, an area known locally as Central House.
The man was suffering from assault-related injuries (serious head injuries) and died at the scene a short while later. Life was pronounced extinct at 03.54hrs by London's Air Ambulance.
While police are satisfied that the victim is a Polish national, they are still in the process of identifying his next of kin. Formal identification awaits, and a post-mortem examination will be held in due course.
Detectives have established that a few hours prior to the incident, around 12:30hrs on Sunday 8 October, the victim was in Yates pub in Bath Road. He was later seen on the street outside the venue in the company of a man and a woman, before the trio all made their way into the alleyway from Lampton Road at around 02:45hrs.
Subsequently, the female was seen to run out of the alleyway back into Lampton Road while a short time afterwards, the male walked out of the alleyway in the opposite direction, into Montague Road and then in the direction of the High Street, Hounslow.
Detective Inspector Will Reynolds, from the Met's Homicide and Major Crime Command (HMCC) leading the investigation, has made a specific appeal to the individuals who were with the victim on Sunday night to come forward.
DCI Reynolds said: "I would urge this man and woman to come forward to police as soon as possible - they are likely to be able to give us information that could prove vital in helping us piece together the chain of events that led up to this tragic event. I would also particularly like to appeal to the local Polish community in west London to contact us if they think they can shed light on the victim or his friends or associates.
"In terms of the wider public, we are very keen to hear from any witnesses who saw the three individuals together in the Yates pub or standing outside afterwards in Lampton Road, or in the area of Central House. The alleyway leads to a car park area of a block of flats which is currently under construction and being refurbished, so it therefore looks like a bit of a building site at the moment.
"We'd also be grateful if anyone who saw the man and woman leaving the scene separately or in nearby streets around 3am to get in touch with us as soon as possible."
Anyone with information is asked to contact the incident room on 0208 721 4005 or call Crimestoppers anonymously on 0800 555 111