Detectives investigating the disappearance of Owami Davies have no new leads after CCTV of her was uncovered last week.
The student nurse, 24, left her family home in Grays, Essex, six weeks ago on 4 July.
She was last seen three days later walking north on London Road, Croydon away from West Croydon.
CCTV enquiries carried out by the Met Police caught the last known image of her at around 12.30pm wearing a dark jacket , red t-shirt, light grey joggers, slider type shoes and carrying a white handbag over her shoulder.
The image of Owami, who was studying at King's College London, is the last known sighting of her.
Five people have been arrested during the course of the investigation for offences including suspected murder and kidnap.
All have since been released on bail.
Owami's desperate family and friends issued another appeal on Monday for help in finding her.
They tweeted: "We try again today, Owami is still missing. No news/sighting of her since.
"Where is she? Why are the cameras not picking her movements? Who took her ? What condition is she in? Where does she sleep? Eat? Dress?
"We have a lot of questions we don’t have answers to. Help us."
Labour MP Dawn Butler also issued a call for people to help, saying: "Please everyone in the area check your video doorbells and CCTVs.
"What has happened to Owami Davies?"
Owami was nearing the end of her studies and due to start a job with Guy's and St Thomas' health trust. She had worked on the A&E frontlines during the COVID-19 pandemic.
Chief Superintendent Dave Stringer said: “I can assure our community that all we can do to find Owami is being done.
"We are working closely with our colleagues in Specialist Crime, who are used to dealing with large, complex investigations and we are providing them all the assistance we can in this extensive inquiry.
"Everyone, I am sure, is hoping that Owami is safe and well and this nightmare for her friends and family will finally end.
"We understand the real anxiety that is currently felt in our community and we have additional officers patrolling to reassure you.
"Please do take the opportunity to speak to these officers about your concerns, they are there to help you and answer any questions you may have."
Anyone with information should call the incident room on 020 8721 4622. Alternatively, call Crimestoppers anonymously on 0800 555 111 or visit www.crimestoppers-uk.org