Police have released new CCTV images and footage of Owami Davies on the night she was last seen in West Croydon.
Owami Davies, of Grays in Essex, left her family home on Monday, July 4.
The 24-year-old was last seen just after midnight in Derby Road in West Croydon on Thursday, July 7.
Officers have now released images of Owami Davies on the night she was last seen in a shop and CCTV footage of her walking in Derby Road.
In particular, officers want to speak to the driver of a white van that was parked in Derby Road that night.
Owami was with a man and crossed the road just as the van pulled out.
Police say the van driver would have had a good opportunity to see them both clearly and are appealing for this possible witness to come forward.
The investigation remains a missing person enquiry.
Three men have been arrested on suspicion of murder as part of this investigation - aged 27, 23 and 32.
Tonight, exactly 28 days after she was last seen in West Croydon, officers will be speaking to the public and handing out appeal leaflets to try and find witnesses and gather more information.
Owami's mum Nicol has said what a "terrible time" this is for Owami's loved ones and is pleading for anyone that can help to contact police.
Detective Chief Inspector Nigel Penney, said: “We are working hard to find Owami but we really do need the public’s help.
"Owami is very vulnerable and the longer she is missing the more we worry that she has come to harm.
"As a result of extensive CCTV enquiries we have a clearer idea of Owami’s movements, but we still need the public to contact us and tell us what they know.
"We would obviously like to speak to the driver of the white van that passed Owami in Derby Road, but anyone with information should call.
"You can call and speak to officers, or if you prefer you can contact Crimestoppers who will never ask your name, trace your call or IP address.
"They are 100% anonymous and you can call them in complete confidence. Owami’s family are living through a nightmare and are desperate for news.
"I would ask anyone who thinks they can help to come forward - as the days pass the anxiety of Owami’s family will only get worse and your call could be the one they are praying for.”
Owami’s mum Nicol Davies said: “There are many friends and family who love and care for Owami and all of them want to see her safe return.
"Owami - if you see this appeal please believe you are not in any trouble, we just want you to come back to us.
"Pease leave a message if you can to let us know you are okay, we are so very worried about you.
"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.”
A spokesperson for the Metropolitan Police said: "Police continue to appeal for the public’s help to find Owami Davies, who has now been missing for four weeks.
"Owami Davies, of Grays, Essex, left her family home on Monday, 4 July.
"She was last seen at around 00:03hrs in Derby Road, West Croydon, on Thursday, 7 July.
"Officers are releasing images of Owami on the night she was last seen in a shop and CCTV of her walking in Derby Road in the hope this will assist the public to recall vital information.
"In particular, officers are keen to speak to the driver of a white van that was parked in Derby Road.
"Owami was in the company of a man and crossed the road just as the van pulled out.
"The van driver would have had a good opportunity to see them both clearly and officers are appealing this possible witness to come forward.
"Although this remains a missing person enquiry, detectives from the Met’s Specialist Crime Command are now leading as they have the resources and expertise required for complex investigations.
"Tonight (Wednesday, 3 August), exactly 28 days after she was last seen in West Croydon, officers will be speaking to the public and handing out appeal leaflets to try and find witnesses and gather more information.
"Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter @MetCC. Please quote reference 22MIS025307.
"To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.
"Three people have been arrested as part of this investigation.
"On Monday, 1 August two men, aged 27 [A] and 23 [B], were arrested in the Croydon area on suspicion of murder.
"A 32-year-old man [C] was arrested on suspicion of murder on Tuesday, 2 August at an address in South Croydon.
"They were taken to a south London police station where they all remain in custody.
"This remains a missing person enquiry."
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