Seven people have been arrested on suspicion of murder after a body was found in a well, sources said.
Gardeners made the grim discovery at a private house yesterday afternoon.
The body is still in the well at the property in Audley Drive, Warlingham, Surrey, and the recovery operation is expected to take some time.
Detective Chief Inspector Cliff Lyons said earlier: "It is a murder investigation. As far as I am concerned, when a body is found in a well it either fell in there or was placed in there, and the evidence is apparent that the body was placed in there."
Two gardeners found the body shortly before 2pm yesterday as they were doing clearing work at the large house, which stands in an acre of grounds in an affluent area.
Mr Lyons said: "The body presents a number of logistical challenges. The well is two feet in diameter, it is seven feet deep to the water line, and the water is approximately four feet deep.
"We need a police marine diving team, with breathing apparatus, and we need to recover the body intact to preserve forensic evidence. The process of recovery is likely to take some time."
He declined to speculate on how long this might be, but it was not going to be quick.
"It is not possible to ascertain with accuracy the gender of the body but, judging by the size, it is most likely to be an adult, not a child. The person is white."
He told reporters at the scene: "It's not been there for an extended period of time, it will be a matter of weeks at the most."
He was not prepared to discuss who lives in the house, or a suggestion that the body was wrapped in carpet. He could not confirm or deny whether the body was intact.
Asked about claims by local residents that there had been quite a bit of trouble in the past couple of years with the people who lived in the house, and that police had been called many times, he said: "The residents have expressed concern, there is intelligence to support that notion, yes."
He said removing the body would take at least the best part of today.
He appealed for anyone who had concerns about a person who has gone missing, especially if they had connections to that area, to come forward.
Anyone with information is urged to call police on 020 8721 4961 or Crimestoppers anonymously on 0800 555111.