i think gug did it because
one one of them is lying
now if GUG is lying (meaning someone else is telling the truth) then that means that he did it
if gug is telling the truth then that wud mean
dave says tony did it...(but he's lying) meaning tony did not do it
tony says that dave is lying when he says that tony did it (since he's lying too) meaning that dave is telling the truth meaning that tony did it
since this is a contradiction... this is not possible
any suggestions??