Police have arrested a fifth person in connection with disappearance of student nurse Owami Davies.
Ms Davies was last seen in the early hours of Thursday 7 July as she walked along Derby Road, West Croydon.
A second unconfirmed sighting has also been reported on the same day, at around 7am, in nearby Clarendon Road.
She had left her family home in Grays, Essex three days earlier - on Monday 4 July.
The Met’s Specialist Crime Command is leading the investigation to establish what has happened to Ms Davies.
They have now arrested five people - two on suspicion of murder and three on suspicion of kidnap - with the most recent being a 27-year-old man arrested on suspicion of kidnap on Saturday 6 August.
Four of those arrested have since been released on bail.
Detectives have renewed their appeal for information, a month on since her last sighting.
Detective Chief Inspector Nigel Penney, who is leading the investigation, said: "This is a complex ongoing investigation involving a significant number of officers.
"We are working tirelessly to follow every line of enquiry, including extensive CCTV trawls, as we continue to search for Owami.
"We are now a month on from the last confirmed sighting of her. I cannot imagine what that time has been like for her family. We continue to provide them with whatever support we can.
"I am grateful for the help we have received from the public so far, but I must again appeal for anyone who has information - however insignificant they believe it might be - to get in touch."
Owami’s mother Nicol Davies has made public appeals through the police for help finding her daughter.
She said: "This is such a terrible time for all those who love Owami and I am pleading for anyone who can help find her to contact police.
"Every day we hope to hear the news that Owami is coming back to us, your help might make it so."
Anyone with information should call the incident room on 020 8721 4622. Alternatively, information can be provided anonymously to the independent charity Crimestoppers on 0800 555 111 or www.crimestoppers-uk.org.
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