Detective Superintendent Lewis Basford, who has been leading the investigation, said: “My team has been working on this investigation for the past eight weeks and we have travelled across the country as part of our searches for this baby.
“We are all truly devastated by the outcome and we know this emotion is also being felt here in Brighton and across the country today.
“While there are still many unanswered questions 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.
“At this stage we have not yet been able to confirm the baby’s gender and a post-mortem examination has not yet taken place.
“Despite this, based on the enquiries we’ve carried out so far, we believe, sadly, the baby had been dead for several weeks before they were found. It’s 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. This is standard protocol for such circumstances.”
Constance Marten and Mark Gordon were arrested in Stanmer Villas, Brighton, at about 21:30hrs on Monday, 27 February, after a member of the public saw them in a shop in Hollingbury Place.
They were initially arrested on suspicion of child neglect. They were later further arrested on suspicion of gross negligence manslaughter. They remain in custody at police stations in Sussex.
The warrant of further detention that was granted yesterday is in place until late this evening (Thursday, 2 March.)
Officers from the Met will remain in the area over the coming days.
Anyone who has information that could support the investigation should call the incident room on 0208 345 3854. We thank the media, public and our policing colleagues in Sussex for their continued support.
The investigation started when officers were called to a car on fire on the hard-shoulder of the M61, near junction four (Farnworth, Bolton) at 18:33hrs on Thursday, 5 January. The occupants were not at the scene. It is believed most of their belongings were destroyed in the car fire.
Enquiries revealed that Constance and Mark were the occupants of the car and that Constance had very recently given birth, possibly one or two days before, and had not been assessed by medical professionals.
A missing person’s investigation was launched by Greater Manchester Police, who established that the family left the vehicle and the motorway safely – walking to the Anchor Lane bridge which links the Highfield and Little Hulton areas.
Officers believe they then travelled to Liverpool and then onwards to Harwich via a taxi at about 03:30hrs on Friday, 6 January.
Mark, Constance and a baby were seen by a member of the public in Harwich at about 09:00hrs on Saturday, 7 January. Officers also received a number of confirmed sightings of the family in Colchester on Friday, 6 January and Saturday, 7 January.
Subsequently, the investigation was handed over to Essex Police on Monday, 9 January.
Essex Police carried out a number of enquiries and reviewed hours of CCTV and were able to place the couple near East Ham Station between 10:30hrs and 12:30hrs on Saturday, 7 January. As this was the last confirmed sighting of the family at the time, the investigation was handed over to the Metropolitan Police Service on Thursday, 12 January.
Detectives then established that they took a taxi from East Ham, being dropped off in Whitechapel Road at 18:14hrs on Saturday, 7 January.
The couple were seen leaving the taxi with an orange carrier bag and a pram. They both had their heads and faces covered and Mark was wearing white plastic bags on his shoes, which he removed a short time later.
At 18:19hrs Mark went into Argos on Whitechapel Road, E1, and bought two big bags full of items, paying in cash, including a blue two-man tent, two sleeping bags and two pillows.
They spent the next few hours walking along the Whitechapel Road area, where they tried to flag down three taxis but were refused. They then walked to the Brick Lane area.
At about 23:46hrs on Saturday, January 7 they then went to Flower and Dean Walk near Brick Lane where they dumped a number of items, including the pushchair. They then got a taxi to Haringey.
At 01:24hrs on Sunday, 8 January, they got in another taxi in Allison Road, Haringey, and travelled to Newhaven, where they were dropped off just outside the port at 04:56hrs.
They then walked to where the A259 crosses over the B2109. They were seen sheltering from the rain, under the overpass, at about 06:00hrs.
At around 06:15hrs on Sunday, 8 January, they walked along Cantercrow Hill into the fields beyond. They were carrying a number of bags and their blue tent.
They were not seen again until a member of the public saw them in a shop in Hollingbury Place, Brighton, at about 21.30hrs on Monday, 27 February. They were subsequently arrested within minutes in nearby Stanmer Villas. They remain in custody at police stations in Sussex.
On the afternoon of Wednesday, 1 March, officers found the remains of a baby in wooded area near to where Constance and Mark were arrested. A post-mortem examination will take place in due course.