Police have arrested a man in connection with the disappearance of university student Joy Morgan.
Welwyn Hatfield Chief Inspector Tannis Perks described the search for Joy, who was last seen in Ilford, east London, on Boxing Day as a "complex missing person investigation".
The Hertfordshire University student, of Hatfield, Hertfordshire, was reported missing to police on February 7.
A 40-year-old man from London has been arrested and released on bail while inquiries continue. Tuesday was Ms Morgan's 21st birthday.
She is black, of slim build, around 5ft 5in tall, with black afro-style hair which she often covers with a scarf. She also wears glasses.
Her family have issued appeal, saying: "We love you, we miss you."
Joy Morgan has links to Ilford, Battersea and Cricklewood in London, as well as Bedfordshire.