A teenager was hospitalised with serious injuries after an alleged assault by a group of between six and 10 men under a railway crossing bridge in Lincoln.
Investigators say the victim, aged 19, was walking under the bridge on Brayford Wharf East at around 3.15am on January 25. He was taken to hospital with a serious head injury and eye fracture.
The group of men are believed to be aged between 18 and 25.
Police carried out extensive enquiries, which have so far failed to identify the offenders.
The force published a witness appeal on Monday, March 2 and anyone who may have seen this group before the incident, or can assist with the investigation, should contact police on 101 quoting reference 20000070889.
It can also be reported via email at [email protected] or by calling the independent charity Crimestoppers anonymously on 0800 555 111.