Refer to 35:19:4:1 and note. See also Oznayim la'Torah, who explains that it applies equally to Shogeg, in which case the Go'el ha'Dam may only kill him outside the Ir Miklat.
Rashi: Which explains why the Torah does not add the words "asher Yamus bah", as it does in connection with other objects ? in Pesukim 17 & 18. Refer to 35:17:1:1.
3)
Why does the Torah insert the (otherwise superfluous) words "Rotze'ach hu"?
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Sifri: To teach us that, if the murderer killed the victim by throwing pieces of metal at him he is Chayav - even though they are not Keilim.
4)
Bearing in mind that the victim may be a T'reifah, and killing him is not subject to Misah, how can Beis-Din sentence a murderer to death? How do they know that the victim is not a T'reifah?
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Chulin, 11b: This teaches us that we go after the majority - since the majority of people are not T'reifos.
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