Ian was in Varna after watching Liverpool FC's Champions League victory in Istanbul.
He said: "There was a scuffle going on and the waiter walked out to tell them to get on their way because they didn't want any trouble.
"One out of around five lads who had run past the shop turned around.
"He started bouncing around on the balls of his feet like a boxer and then came face to face with Martin.
"I saw him strike a sudden blow with his right arm landing a blow to Martin's face leaving him motionless face down on the floor. I saw another youth run up and kick him.
"Then, Sankey ran over and I saw him hit Martin on the head with this piece of stone that I have described."
The ECHO published an appeal a couple of months ago asking for Ian to come forward after another Liverpool supporter told the Shields family that a witness had spoke to him and told of seeing a "big, fat lad with dark hair" drop the paving slab.
Ian said he had not come forward previously as he believed Sankey's signed confession would result in Michael Shields's immediate release.
He said: "I didn't realise so many people would tell lies to get a lad locked up."
