The family of Neil Buchel have been informed of the discovery of a human leg in a lake in Dagenham although police said it was too early to confirm if the find is linked.
The 39-year-old went missing from Braintree Road, Dagenham, on March 13 and further enquiries by police raised suspicions around the circumstances of his disappearance.
Police said Mr Buchel was involved in an altercation with a group of males on the day of his disappearance.
He then returned with others to an address in Stansgate Road and has made no contact with family - including his estranged partner and two daughters - since.
Three men arrested in the murder investigation have previously been bailed.
More top news
The London Mayor has made some forthright comments about Britons who have been lured to join Islamic State.
Bright spells with rain, sleet and snow showers at the weekend.
As soon as the information went missing in early January, the Ministry of Justice say they launched an urgent investigation.