I was there too, sitting in the pub, and saw poor Mark Smith get his head kicked as he lay in the road. But he got up, and even went to the match, and didn't die until after the game. Later I rued not following the bloke who kicked him so that I could identify him, but Mark got to his feet and I got back to my pint. My everlasting shame.
I was a (useless) witness at the trial, when a whole bunch of thugs got off.
Useless fact - the trial at Winchester was taking place at the same time as three alleged members of the IRA were on trial for Conspiracy to kill Tom King at his home in Castel Combe - I was working on that trial and tracking the Swindon trial at the same time.
Trust me, you can't blame yourself for what you could have done - you weren't to know he would die later on; what you do know si that if you had known he would die, you would have done the right thing.