Human remains have been found in woodland on the Royal Family's Sandringham Estate by a member of the public.
Detectives from Norfolk Constabulary launched an investigation after they were alerted to the discovery at Anmer, near King's Lynn, on New Year's Day.
The area was sealed off and a detailed search was being carried out tonight.
The force said in a statement: "Detectives from Norfolk Constabulary have launched an investigation following the discovery of human remains in an area of woodland at Anmer, near King's Lynn.
"The remains were found by a member of the public who reported the incident to police on Sunday January 1 shortly after 4pm.
"The area has been sealed off and a detailed search is currently being carried out."
Buckingham Palace said it had no comment to make as it was "a matter for Norfolk police".