A body found on the Queen's estate was that of a young adult woman and had been at the site for between one and four months, police have said.
Detectives investigating the death are examining links to cold cases nationwide after the remains were discovered near to the village of Anmer on the Sandringham estate in Norfolk.
They were spotted by a dog walker shortly after 4pm on New Year's Day in woods on farmland about a mile from the main gate to Sandringham House.
A Norfolk Police spokesman said: "The pathologist believes it is highly unlikely the death was through natural causes. There is no evidence of accidental injury, damage due to firearms or bladed weapon. Samples have been taken which should provide a DNA profile within the next 24 hours."
Speaking to journalists at the scene, Detective Inspector Jes Fry said: "How far back this investigation goes depends on what the experts say. We are looking at missing persons reports nationwide as well as cases we have been working on more locally for potential links."
He added: "I cannot confirm whether she was clothed because at the moment only my staff, the person who found the body and the person or people who put it there know that and I would like it to stay that way. The body was found by a dog walker and was not underground. At this stage we do not know who the victim is."
Mr Fry said it was not yet clear if the woman was killed at the scene or taken there after death. He said police had informed the Sandringham estate about the find and officers responsible for protecting the royals had been updated on the situation.
Pathologist Nat Cary arrived at the site on Tuesday morning to examine the body and entomologists were looking at insect life on the body to establish how long it had been there.
The Queen and the Duke of Edinburgh are currently in residence at Sandringham, along with the Earl and Countess of Wessex.
One Anmer resident said: "We were all aware of the police activity and normally in this area gossip travels fast. But at the moment we know very little other than the fact a body has been found."