The family of Adam Hird have increased the award they are offering from £1,000 to £3,000 for the woman who police believe filmed the incident outside Club 65, Albert Embankment to come forward.
Adam Hird was restrained outside the club at approximately 3.20am on Sunday 15th June 2014, and died two days later.
Anyone who witnessed the incident on Sunday morning is asked to call the incident room on 020 8721 4054. Officers believe that other members of the public may also have video footage of the incident that could assist the investigation.
To remain anonymous, call Crimestoppers on 0800 555 111.