Met Police Detective Superintendent Lewis Basford said the couple had not given them information about the child’s whereabouts or even disclosed its gender.
“We now have to consider the possibility that the baby has come to harm,” he told reporters.
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0:27
Missing couple moments before arrest
He said he still hoped the baby could be found alive but that the cold weather was an obvious risk to its safety.
“Clearly the risk is getting higher… this may not end in the way we would like, but we need to remain hopeful,” he said.
He added they were still open-minded about the possibility the child may have been given to someone else to look after.
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11:55
Police search for missing baby
Chief Superintendent James Collis, from Sussex Police, said the search area was “vast” at about 91 square miles and centred on land between Brighton and Newhaven – about seven miles further down the coast.
He also appealed for people to contact the force with any information or potential sightings over the last few weeks.
Marten’s father, Napier Marten, told The Independent it was “an immense relief” to know the couple had been located but “very alarming news her baby has yet to be found”.
“And if the victims come forward to me in this victims panel and they say, ‘actually, we think there needs to be a national inquiry into this’, I’ll listen to them.”
Her comments come days after it emerged she had rejected calls from Oldham Council to hold a government inquiry into grooming gangs in the town, and said the council should commission one instead.
That has led to tech billionaire Elon Musk attacking her and Sir Keir Starmer for not holding a national inquiry and accusing the prime minister of being “complicit” in the abuse.
Professor Alexis Jay finished an eight-year national inquiry into child sexual abuse in 2022 and set out recommendations for the government.
She said: “The measures that I’m setting out today and the legislation in many ways go further because it puts a requirement on all councils to have teams working to keep children safe.
“And the bandwagon jumpers that have come along in recent days, they don’t care about children, they don’t care about making sure that we stop this and we take action.
“They had years to do it and they didn’t do it.”
The Conservatives also rejected a call from Oldham Council for a government inquiry in 2022.
You can listen to Beth’s full interview with Jess Phillips in a special episode of Electoral Dysfunction released on Thursday.
The 14-year-old who was stabbed to death on a bus in southeast London yesterday has been named as Kelyan Bokassa.
He was stabbed to death on a bus in Woolwich Church Street, close to the Woolwich Ferry, just before 2.30pm on Tuesday.
The teenager died at the scene shortly after medical help arrived.
The Metropolitan Police called the stabbing a “horrific attack,” while London mayor Sir Sadiq Khan said the “heart-breaking violence has absolutely no place in our city”.
No arrests have been made so far but officers are appealing for witnesses who were on the 472 bus.
An aspiring rapper, 14-year-old Kelyan was also “briefly” a student at St Columba’s Catholic Boys School in Bexleyheath.
The South East London Catholic Academy Trust said in a statement it was “saddened by the loss of life” and added: “Our thoughts and prayers are with his family and friends at this difficult time.
“Our schools will provide support to any of the students who may be affected by this senseless violence.”
Mary Bokassa, the boy’s mother, also told MailOnline that he and others “were taken advantage by gangs” and “were groomed”.
She told the outlet: “He was missing for a year and was living on the street. He finally turned up at my doorstep, he was sick, underweight and tattooed.
“He was exposed to drugs. He probably experienced something because I could sense it. He was not himself. If I questioned him, he wouldn’t tell me anything about his friends.”
Detective Chief Inspector Martin Thorpe, who is leading the investigation, said: “Following Kelyan’s tragic death yesterday, specialist officers are now leading the investigation which is progressing at pace.
“If anyone saw this horrific attack or was in the area then I urge them to come forward and speak to officers.
“We’re particularly interested in any mobile phone footage that captured this incident or any dash cam or doorbell footage from around the surrounding area at the time of this incident.”
UK Athletics Ltd and a former head of sport for a major London games have been charged with manslaughter following the death of Paralympian Abdullah Hayayei, the Crown Prosecution Service said.
United Arab Emirates athlete Mr Hayayei died aged 36 after a metal throwing cage fell on him while he was shot put training at Newham Leisure Centre in London in 2017.
The Paralympian was pronounced dead at the scene after he was struck by a metal pole in the incident.
He was training in preparation to represent his country in the shot put, discus and javelin at the World Para Athletics Championships which began in London later that week.
Teams and coaches from several nations were present at the time of the tragedy.
Keith Davies, 77, the former head of sport for the 2017 World Para Athletics Championships, has been charged with gross negligence manslaughter and a health and safety offence.
UK Athletics has been charged with corporate manslaughter and a Health and Safety at Work Act offence.
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Both UK Athletics and Davies are due to appear at Westminster Magistrates’ Court on Friday 31 January.
Malcolm McHaffie, head of the CPS Special Crime Division, said: “The Crown Prosecution Service reminds everyone that criminal proceedings are active and both UK Athletics Ltd and Davies have the right to a fair trial.
“It is extremely important that there be no reporting, commentary or sharing of information online which could in any way prejudice these proceedings.”
The Met Police launched an investigation following Mr Hayayei’s death on 11 July 2017, with the Crown Prosecution Service saying today that it has authorised charges following a review of evidence provided by the force.
Mr Hayayei made his Paralympic debut in Rio de Janeiro in 2016 and was set to feature in his second World Championships in 2017.
Ed Warner, who was co-chair of London 2017, said after Mr Hayayei’s death: “This is a devastating event and everyone within the London 2017 Organising Committee is shocked and saddened.
“We will be working closely with all the competitors and teams over the days ahead to offer support wherever it is needed.”