And whence is it derived that if he does not die by the hand of the witnesses anyone can put him to death? From "and the hand of all the people afterwards."
"and you shall remove the evil from your midst': Remove the doers of evil from Israel.
(Devarim 17:8) "If there be hidden ("ki yipale") from you a thing of judgment": "ki yipale": Scripture here speaks of the mufla (expert [similar to "yipale"])