The three men who were shot were said to be affiliated with the Hackney Turks organised crime gang, who had a rivalry with the Tottenham Turks, with whom Riley had links, jurors had heard.
The gunman remains at large but prosecutors said Riley had played a “key role” before, during and after the shooting.
Scotland Yard has offered up to £15,000 for information leading to the identification, arrest and prosecution of the person who fired the shots.
During a three-week trial, Riley was asked to identify the “third party” who had recruited him for around £40,000.
He refused, citing fear for his life and that of his family.