I think there's a topic about that around here somewhere.
the man who did all the legwork over decades on this himself says there are a few points in history where the body of alexander (or mark, post-venice) might have been replaced. but the other macedonian artefacts associated with st mark’s relics plus associated history (the sarcophogus in london?) make a compelling case of a possibility of continuity with alexander’s tomb.
what is that macedonian partial stone facing piece that apparently perfectly fits the container alexander was in doing in st marks?