A man whose body was found in a well had been assaulted, police have said.
An initial post mortem examination could not find a cause of death but the examination did reveal injuries consistent with an assault, according to a Scotland Yard spokesman.
The body was discovered by two workmen doing clearing work in the front garden of a large house in Audley Drive, Warlingham, Surrey, on Friday and recovered by specialist police officers.
Seven men aged between 21 and 27 who were arrested on suspicion of murder have been bailed to a date in late December, pending further investigation.
The post mortem examination, carried out at East Surrey Hospital mortuary, confirmed that the body is male. The victim's identity has not been established.
Detective Chief Inspector Cliff Lyons said: "This is an unusual case and I would appeal for anybody who has concerns about a missing person, or who believes they may know something about this individual or incident, to call my officers.
"The post mortem examination has revealed this person, who we now know is a white male, suffered injuries before being placed into the well. We are treating the incident as a murder."
He added that judging by the size of the body it was likely to be an adult.
Anyone with information was urged to call police on 020 8721 4961 or Crimestoppers anonymously on 0800 555111.