Scotland Yard said a body found in Boston Manor Park, west London, on Saturday has been formally identified as that of Arnis Zalkalns - the prime suspect in the Alice Gross murder investigation.
Scotland Yard Commander Graham McNulty said officers had not yet formally identified a body found in the River Brent last night but said they disappearance of Alice Gross was now a murder investigation.
He said "significant efforts" had been made to conceal the body.
Police previously searched the area where the decomposed body, thought to be that of Alice Gross murder suspect Arnis Zalkalns, was found.
A body thought to be Alice Gross murder suspect Arnis Zalkalns was badly decomposed and could have been in a west London park for a month.
The ex-mother-in-law of a suspect sought over the murder of West London teenager Alice Gross has spoken to ITV News.