Police have announced that a body has been found in wooded area in the search for the two-month-old baby of Constance Marten and Mark Gordon.
The “heartbreaking” news was announced by officers at a press briefing on Wednesday evening.
Speaking to reporters, Met Detective Superintendent Lewis Basford said: “This is an outcome that myself and that many officers who have been part of this search had hoped would not happen.
“I recognise 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.”
A post-mortem examination will be held in due course, he added, while further work by officers at the location will continue.
Mr Basford urged members of the public to avoid “speculation and comments online” that could be prejudicial to court proceedings.
Chief Superintendent James Collis from Sussex Police said the announcement would be “heartbreaking” for the local community.
“I would like to thank again the public, including the member of public whose information led to the arrests, the huge number of people who came forward with information and those that have volunteered to assist with the searches.
"We continue to support the Metropolitan Police as they conduct their investigation and also the wider community as we all come to terms with this tragedy.”
It comes a day after the pair were rearrested on suspicion of gross negligence manslaughter following 54 days on the run.
The aristocrat and her partner were located by officers from Sussex Police in Stanmer Villas, Brighton after a member of the public reported seeing them shortly before 9.30pm on Monday. The baby was not with them.
Detectives on Wednesday applied for an extra 36 hours to question the couple, admitting that it was possible the baby may have “come to harm” during their investigation.
Hundreds of police officers and search and rescue experts had been scouring 90 square miles of the Sussex countryside in a bid to find the baby, who has born in a car in Bolton on January 5.
Officers from London Search and Rescue were seen searching Moulsecoomb Wild Park, around a mile from where the couple were arrested, on Wednesday.
A uniformed officer was seen standing guard at the entrance to the park, with dog walkers saying they saw police tape cordoning off parts of the woodland.
Gordon and Marten disappeared on January 5 after their abandoned car was discovered on fire on M61 near Bolton.
They had used taxis to first travel to Liverpool, then Harwich in Essex, and on to east London, before arriving in Sussex on January 8, police said.
Detectives previously revealed that they had avoided detection by only making payments in cash, hiding their faces on CCTV and often moving around at night or in the early hours of the morning.
Marten, who is from a wealthy aristocratic family, was a promising drama student when she met Gordon in 2016.
Since then the couple have led an isolated life and, in September, as Marten’s pregnancy progressed, began moving around rental flats.
CCTV footage from just before they were caught appears to show Gordon limping and using a large stick to walk.
During the search for the family both Marten's parents, from whom she was estranged, made public appeals for her to hand herself in.
On Tuesday her father, Napier Marten, expressed his immense relief that she had been found, but said he remained alarmed that the baby was missing.
