It is law to have a passport fo ryour horses here. It costs us €25 to get one, and it's very simple and easy to do. As for microchipping, all of our TBs are chipped. We have to chip American breds when they arrive here, and it takes all of 2 seconds to do.
Surely your friend has photographic evidence somewhere of this horse being on his property? Can the vet not stand up and say that he has treated the horse before, and a blacksmith say the same?
Anyway, as other people have said, it's amazing he didn't file a police report. If somebody stole either of my boys I'd be on the phone to every gardai station in the country and posting it on every webpage imaginable until I got them back. Not only that, but a missing or strayed horse runs the risk of being hit by cars/injuring themselves or somebody else.
Stop for a minute, open your mind, learn. You may not agree with what I say, I may not agree with what you say but we will both learn something new.