It's confirmed that FBI sniper Lon Horiuchi was present at Waco in an overwatch position. Another sniper going to relieve him said the sniper hide was full of empty shell casings when Horiuchi left which one could assume means he was in there popping off rounds all the live long day. He absolutely was the one that shot Vicky Weaver in the face while she was holding her baby. There's no disputing that.