A man allegedly stole medical equipment from the back of an ambulance as paramedics went to the aid of a patient at Scunthorpe General Hospital.
Humberside Police published an image of 48-year-old John Teanby, who they wish to speak to in connection with the incident.
Police believe he may be in the Scunthorpe area, but have not yet been able to track him down despite extensive enquiries.
However, the force did not specify whether he is a suspect or a witness.
Anyone with information is being urged to contact Humberside Police on 101.