A man was punched in the head and robbed of his wallet in Northampton town centre.
The attack happened near the Jaguar Garage on Kettering Road on April 22 between 11.45am and 12.05pm.
The victim was approached by another man who punched him in the head and stole his wallet.
The suspect is described as a white man, in his 30s, about 6ft, with brown hair and wearing dark clothing.
Witnesses or anyone with information should contact Northamptonshire Police on 101. Information can also be shared via Crimestoppers in confidence on 0800 555111.