Officers are investigating an incident on Thursday 8 September in Bournemouth in which a woman in her 60s was bitten by a dog.
She was using a pedestrian crossing at around midday, on Holdenhurst Road in the Springbourne area, when a man came towards her with, what's believed to be, a Malinois-type dog.
The dog bit the woman on her arm - leaving a deep wound.
People around her came to her aid - but the dog owner left without leaving his details.
The man with the dog is described as being aged in his 40s with long brown hair.
Police Constable Jennie Sykes-Martin, of Dorset Police, said: “This incident left the victim with a nasty injury, and we are carrying out enquiries to identify the dog owner involved.
“I would urge anyone who recognises the man from this image to please contact us.”
Anyone with information is asked to contact Dorset Police at www.dorset.police.uk/contact or by calling 101.