William Kerr, 53, was jailed for life for murder at Leeds Crown Court on June 26, 1998, and released on licence on January 23, 2015.
He is wanted on emergency recall to prison after breaching his licence by absconding from approved premises in Hull.
Kerr has links to the Humberside, West Yorkshire and London areas.
Detective Inspector Eamonn Clarke, of North Yorkshire Police, said: “To assist our already extensive efforts to trace William Kerr, I am urging people to keep an eye out for the man in the photographs.
“We ask that you do not approach Kerr, as he is considered dangerous. You should contact the police straight away on 999 and officers will be despatched to arrest him or investigate the sighting.”
DI Clarke has also appealed to Kerr.
He said: “William, you know you have breached your licence conditions, and by continuing to do so you are only making things worse. It is now time to do the right thing and hand yourself in to the police.”
Anyone with information should call 999 and tell the operator they are calling about the William Kerr appeal. Alternatively, people can call Crimestoppers, anonymously, on 0800 555111. They should quote North Yorkshire Police reference 12150049525 and tell the operator it is urgent.