(CNN)The body of a baby has been found in a woodland area in southern England, close to where aristocrat Constance Marten and her partner Mark Gordon were arrested earlier this week over concerns for their child's welfare, UK authorities said Wednesday.
"It is my very sad duty to update that this afternoon, police officers searching a wooded area close to where Constance Marten and Mark Gordon were arrested, discovered the remains of a baby," Detective Superintendent Lewis Basford of the Met's East Area Command said in a statement on Wednesday.
"A post-mortem examination will be held in due course," the statement continued.
Marten, 35, and Gordon, 48, were arrested earlier this week after going missing in early January. They were believed to be traveling with a newborn.
On Tuesday, London's Metropolitan Police said in a statement the pair had been "initially arrested on suspicion of child neglect," but were later "further arrested on suspicion of gross negligence manslaughter."
Police helicopters, sniffer dogs, thermal imaging cameras and drones were used to assist over 200 officers on the ground in their search for the baby, after couple were spotted Monday in Brighton, southern England, and arrested.
A crime scene has now been established around the infant remains, where work is expected to "continue for some time," Basford said.
"This is an outcome that myself and the many officers who have been part of the search, had hoped would not happen," he said. "I recognize the impact this news will have on the 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."
Searching since January
The search for the couple and newborn began in early January, with police releasing several appeals and offering a £10,000 ($12,090) reward for information that would lead to their discovery.
Marten is the daughter of aristocrat Napier Marten, a film and music producer. In an audio appeal to his daughter, published by UK news outlet The Independent last month, Napier Marten said Constance was "much, much loved, whatever the circumstances," adding that the family was "deeply concerned" for her and her child's welfare.
"Darling Constance, even though we remain estranged at the moment, I standby, as I have always done and as the family has always done, to do whatever is necessary for your safe return to us.
"I beseech you to find a way to turn yourself and your wee (little) one into the police as soon as possible so you and he or she can be protected. Only then can a process of healing and recovery begin, however long it may take, however difficult it may be," he added.