TT #126 · Parashas Reeh · Third Aliyah · Passuk 13:6
And that prophet or that dreamer of a dream shall be put to death, for he has spoken falsity against Hashem your God Who brought you out of the land of Egypt and Who redeemed you from the house of bondage, to make you stray from the way that Hashem your God commanded you to walk in; and you shall purge the evil from your midst.
Torah Temimah points to Chullin.
English: “And you shall purge the evil from your midst” — A murderer whose verdict has not yet been finalized and who fled — it is a mitzvah to bring him back to the court and to fulfill with him “and you shall purge the evil from your midst.”
Derash on the verse (Chullin) — extending the duty to purge evil to a fleeing murderer whose trial is incomplete.
One is obligated to return a fleeing murderer (prior to final verdict) to the court so that the evil may be purged from the midst of the people.