Back to my original point, initially he was so convinced of what he saw and after interference by McCann agents it got watered down. In any country that is called interfering with a material witness and comes with a penalty. I only wish Martin Smith would set the record straight here and now and tell us exactly what went on. Now there's a challenge to him!!
What do you mean by "initially"? It only occurred to him that it might have been Gerry when he saw the news coverage of how Sean was held when Gerry walked down the plane steps, just after they'd been made arguidos, no less.
As I and others have posted numerous times before, there is a body of research into "false memories" generated by the mind attempting to reprocess new "information". That doesn't mean that a "flash memory" is always inaccurate, but officers aware of the phenomenon and trained in how to explore it further with a witness would be far more competent than officers who aren't.