Officers are keen to trace a man with a small white dog as part of their investigations after a boy aged 14 was assaulted while in Stoke Gifford.
The boy was punched in the face in the car park of the Engineering Academy in New Road at about 8.45am on Thursday January 8.
The man pictured was in the car park at the time and left on foot. He is described as being middle-aged and white, dressed in black. He wore a black baseball cap, a black snood and black and white trainers.
Police enquiries have yet to identify the man, who may have information which could help.
Please call 101 and give the reference 5226006268. Alternatively contact the independent charity Crimestoppers anonymously by calling 0800 555 111 or visit them online at crimestoppers-uk.org/give-information