How many arrests have been made for witnesses caught lying to a grand jury? Is this our “new normal” now? We have a president and half of congress lying to us all the time. What happened to “the truth, the whole truth and nothing but the truth”.
I don’t know if you can (or should) prosecute witnesses who gave accounts that were unsupported by the physical evidence; if someone believes what they saw then there really isn’t much you can do about it (without endagering future witnesses everywhere). I do think they should prosecute to the fullest extent of the law those “witnesses” who later admitted they hadn’t even been there and were relaying what they were told.