A man has been arrested on suspicion of murdering a mother of two young children.
Janelle Duncan-Bailey, 25, has not been seen since she went missing in south London in the early hours of Wednesday.
On Friday night, a 30-year-old man was arrested on suspicion of her murder, Scotland Yard said. He was taken to a south London police station, where he remains in custody.
Ms Duncan-Bailey, of Pawsons Road, Thornton Heath, London, left her children - boys aged two and seven - with a friend in Bromley while she attended a family function, police said. She left the friend's at about 4am on Wednesday to return to Thornton Heath, where at about 4.30am she visited her former partner's home.
Police were called after reports of a domestic incident and Ms Duncan-Bailey left the address with officers.
It is believed she asked to be taken to another friend's house in Limpsfield Avenue, Thornton Heath, and she was last seen between 5am and 5.30am walking towards flats in Limpsfield Avenue.
Ms Duncan-Bailey was reported missing later that day after she failed to collect her children.
A spokesman for the Metropolitan Police said: "Janelle has never been missing before and her disappearance is totally out of character."
She is described as being black, about 5ft 5in, of medium build and with shoulder-length black hair which may have been enhanced with hair extensions.
Police are appealing for anyone with information about Ms Duncan-Bailey or her whereabouts to contact detectives from the Specialist Crime Directorate at Sutton police station on 0208 721 4054, or Crimestoppers on 0800 555 111.