Police are appealing for witnesses following a reported assault on Lincoln High Street.
The incident happened at around 4.25pm on July 7 in the alley at the side of Primark.
A man intervened in what he believed was a robbery and was assaulted for doing so.
A spokesperson for Lincolnshire Police said: “We are looking to speak with the person pictured as part of our inquiries.
“If you have information please report it by calling 101 quoting incident 341 of July 7.”
To report anonymously, call Crimestoppers on 0800 555 111.
UPDATE: A Lincolnshire Police spokesperson said on July 26: “We received a report of alleged assault on 7 July in good faith. Thanks for all your help with our appeals into the incident.
“This has now all been resolved as no offences have been committed.”