The victim, who is 21-year-old, was assaulted by a large group of men in Hoglands Park, Southampton, on Saturday, March 23.
He had his bank card stolen and suffered stab wounds to his arm.
The victim then left the park and sought help in St Mary’s Place and police were called to the scene at 1.28pm on March 23 by the ambulance service.
Officers investigating the robbery would like to identify the person in the picture above as they believe he may have information than can assist their investigation.
Police would like to hear from anyone who was in that area at that time and saw what happened, or who may have mobile phone footage of the group involved in the assault.
Four teenage boys have been arrested in connection with this incident.
All have been questioned by officers and released from police custody but remain under investigation.
Anyone with information is asked to contact police on 101, quoting Operation Kim or 44190101364.
Alternatively you can call the charity Crimestoppers anonymously on 0800 555 111.