Police have released CCTV showing four potential witnesses who may be able to help their investigation into the disappearance of student Libby Squire.
The 21-year-old was last seen on a night out with friends in Hull 18 days ago.
A cyclist, a pedestrian and a pair walking together in Oak Road between 1.13am and 2.34am on 1 February are seen in the footage released by Humberside Police on Tuesday.
All are too far away to be easily recognised.
The last sighting of the student is believed to be on Beverley Road at the junction with Haworth Street at around 12.05am.
Miss Squire was wearing a black denim skirt, a faux leather jacket and trainers. Police released images of similar items earlier in the search.
The force said the quartet all appear to have come from the direction of areas including the playing fields where investigators have been searching.
Detective Superintendent Martin Smalley 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 four 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 to assist with our inquiries.”
Earlier this month, police released CCTV showing the last-known movements of Miss Squire, who is originally from High Wycombe in Buckinghamshire.
The footage shows her walking towards The Welly Club in the city at 11.18pm, unsteady on her feet as she negotiated snow that fell earlier that day.
Miss Squire can be seen with friends at one point, one in a winter coat who appears to loop arms with her as they wait to get into the club.
Less than five minutes later Ms Squire was turned away as doormen thought she was too drunk, so she got into a cab to head home.
DS Smalley admitted earlier this month that she “may have come to some harm”.
Five days after her disappearance, Pawel Relowicz, of Raglan Street, Hull, was arrested and questioned on suspicion of abduction.
He appeared before magistrates charged with a number of offences unrelated to Miss Squire’s disappearance, which police said he remains under investigation for.