Remains have been found in the search for the two-month-old baby of Constance Marten and Mark Gordon, Detective superintendent Mark Basford of the Metropolitan Police said.
Hundreds of police officers and search and rescue experts have been scouring 90 square miles of the Sussex countryside in a bid to find the baby, who has not had any medical attention since being born in a car in Bolton on January 5.
Speaking at Sussex Police headquarters, he said: “It is my very sad duty to update this afternoon, police officers searching a wooded area close to where Constance and Mark Gordon were arrested, discovered the remains of a baby.
“A post mortem examination will be held in due course.
constance marten missing baby
“A crime scene is in place and work at the location is expected to continue for some time.
“This is an outcome that myself and that many officers who have been part of this search had hoped would not happen.
“I recognize the impact this news will have on many people who have been following this story closely and can assure them that we will do everything we possibly can to establish what has happened.”
The couple remain in custody having been arrested on suspicion of child neglect and gross negligence manslaughter.
Marten, 35, who comes from an aristocratic family with royal connections, first went missing with boyfriend Mark Gordon, 48, when their car was found abandoned and on fire at the edge of the M61 on January 5.
From there they travelled around the country by taxi, avoiding police by paying for everything in cash, covering their faces while on CCTV and moving locations frequently, often after dark.
They were finally arrested in Brighton on Monday, minutes after a member of the public tipped off police, but their baby was not with them.
They refused to tell police where the baby was, sparking a massive hunt across a wide area of the Sussex countryside.
More than 200 officers and specialist search teams scoured the area around Stanmer Villas, where the couple were finally caught after a tip-off from a member of the public.