A dead body was discovered yesterday in the river at Crane Park Island in Twickenham.
Police were called shortly after 11am on Monday to reports of the body of a man in the water.
He was recovered by the Marine Policing Unit and pronounced dead at the scene.
Police believe they know the man’s identity but are awaiting formal identification.
The death is being treated unexplained, with the postmortem examination due to take place this afternoon.
Anyone with any information is asked to call police on 101 or Crimestoppers anonymously on 0800 555 111.