what if an umpire sees ball tampering?

if the cameras don't pick it up he doesn't have any hard evidence (other than the ball itself, though in this case it is impossible to prove any damage was done by players and not spectators given that the ball had been in the crowd a few times). Should he still call it if he sees it - even if it is impossible for him to subsequently prove it?

Posted By: mr carra, Aug 21, 10:29:00