Police looking for Libby Squire want to speak to four people seen on CCTV near where the Hull student went missing.
The 21-year-old from Buckinghamshire was last seen at about 00:05 GMT on 1 February near her student home.
Searches have taken place on land and in a lake at Oak Road playing fields, with the CCTV showing people on Oak Road shortly after her last sighting.
Humberside Police said the four people "may have seen or heard something that could be vital to the investigation".
The grainy footage shows the individuals on Oak Road near the junction with Clough Road between about 01:15 and 02:30.
One person is seen running, a cyclist is pictured twice in the space of ten minutes and two people are seen walking together.
Police said the last sighting of the University of Hull student was in Beverley Road, close to where she lived.
Dozens of police officers have been searching undergrowth and waterways in Oak Road playing fields, a few streets away from her home on Wellesley Avenue.
Det Supt Martin Smalley, who is leading the investigation, said: "These four people are potentially witnesses who we need to identify and speak to as part of the investigation.
"While the footage isn't clear enough for anyone to recognise who they may be, the people in the clips will know if they were in that area at the times given and I would ask them to please come forward."
Police searches continue to take place near Oak Road and the River Hull, the force said.
"The investigation is very much ongoing and active, with one man continuing to remain under investigation while we further our enquiries," Det Supt Smalley added.