Police believe the baby of Constance Marten and Mark Gordon may have been dead for “several weeks”, Detective Superintendent Lewis Basford of the Metropolitan Police said.
Officers have not yet been able to confirm the baby’s gender and post-mortem examination hasn't yet taken place.
Detective Superintendent Basford said officers investigating the case were “devastated” by its outcome as he confirmed Constance Marten and Mark Gordon remain in custody.
Flowers have been laid near where the couple were arrested on Monday.
Police have been searching for Constance Marten and Mark Gordon's missing baby
PA
Officers say the case has now been referred to the police watchdog.
Speaking at a press conference on Thursday, the Metropolitan Police said: “At this stage we have not yet been able to confirm the baby’s gender and post-mortem examination has not yet taken place.
“Despite this, based on our inquiries we’ve carried out so far, we believe sadly the baby may have been dead for some time before they were found.
“It is too early for us to provide a more specific date.
“Because we believe the death occurred during the course of a missing person investigation we have made a mandatory referral to the Independent Office for Police Conduct (IOPC). This is standard protocol for such circumstances.”
Met police officers will remain in the Brighton area over the coming days as inquiries continue and a warrant for further detention granted on Wednesday will last until Thursday evening.
“We are truly devastated by the outcome and we know this emotion is being felt here in Brighton and across the country today," Superintendent Basford added.
“We know there are still many unanswered questions, and it is important that we give the investigation team the time and space they need to establish more details about the circumstances of this tragic death.”
Police had been “overwhelmed by kind messages and support” from the public as they carried out the search for the infant, Chief Superintendent James Collis of Sussex Police said.
He also thanked “the huge number of people who have helped or offered to help in any way that they can”, adding: “It is truly appreciated.”
Flowers have been laid near to where Constance Marten and Mark Gordon were arrested
PA
Constance, known as “Toots” to friends, disappeared with her partner Mark Gordon and their newborn baby on January 7.
The pair went missing just two days after abandoning a burning car on the motorway in Bolton.
They travelled by taxi from Bolton to Liverpool, to Harwich in Essex, before heading to east London and finally Newhaven in Sussex, where they were seen near the ferry port on January 8.
The couple were arrested in Brighton on Monday amid a huge search for their missing baby.
