Detectives are keen to speak to this man in connection with the death of David Cameron, in Consett, last month.
The man is being treated purely as a witness and is not in any trouble.
It is believed the unknown man was walking down Medomsley Road, in Consett, near to The Braes Bar, when he may have seen Mr Cameron.
A short time later Mr Cameron was involved in an altercation in Southernwood, at about 5.33pm on December 5.
The 47-year-old was sadly pronounced dead a short time later at the scene.
A14-year-old boy arrested in connection with the incident and is currently on conditional bail.
The unknown man or anyone else who was in the area at the time is asked to get in touch with detectives at Durham Constabulary on 101.