He was arrested several hours after the attack but has always denied playing any part in it - insisting he was asleep in his hotel room at the time and was a victim of mistaken identity.
Another Liverpool fan, Graham Sankey, has since admitted responsibility for the attack but the Bulgarian court rejected his confession.
Another Liverpool fan, Anthony Wilson, was cleared of hooliganism and convicted of possession of cannabis. He received a two and a half year suspended sentence.
Shield's family plan to appeal against the conviction.