Gavin Williams was 28 when he was killed in Chicago on December 16, 2012. His death occurred during a year that saw a sharp rise in violence in the city, with 506 homicides reported in 2012 compared with fewer the year before.

Observers linked the increase in killings to several factors mentioned at the time: unseasonably warm weather, the disbanding of specialized gang units that had been deployed to high-risk areas, and wider social challenges affecting the city.

If anyone knew Gavin, was with him that day, or has information about what happened on December 16, 2012, please come forward.