Detectives have released an image of Mohammed Hussein, aged 33, who is suspected of a serious sexual assault on a 32-year-old woman at her home in the Layerthorpe area of the city.
Hussein, who is originally from Bangladesh, was known to the victim prior to the incident on 20 August 2012.
Officers have been making extensive enquires in an effort to locate Hussein, who is known to have links to both London and Brighton.
Detective Sergeant Alan Rowan, of York CID, said:
It is imperative that Mohammed Hussein is arrested as soon as possible so that we can progress the investigation and give reassurance to the victim.
We don’t know if Hussein is still in York at this time or possibly in London or Brighton but I am urging the public to take a good look at his picture and get in touch with the police or Crimestoppers if they see him.
Anyone who can help to trace Mohammed Hussein is urged to contact North Yorkshire Police on 101 – select option 2 – and ask for Alan Rowan or York CID.
Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.
Please quote reference number 12120138060 when passing information about this incident.