94 Sotah 9/2-5

(2) If [the corpse] was found buried underneath a heap of stones, or hanging on a tree, or floating on the surface of the water, they would not break [the heifer’s neck], as it says: “In the earth” — and not buried underneath a heap of stones, "fallen" not hanging on a tree; “In a field” —and not floating on the surface of the water. If it was found near the border, or a city whose majority of inhabitants were non-Jews, or a city in which there is no court, they would not break [the heifer's neck]. They measure the distance only from a city in which there is a court. If [the corpse] was found exactly between two cities, both of them would bring two heifers [between them], the words of Rabbi Eliezer; And Jerusalem does not bring a heifer whose neck is to be broken.

(3) If the head was found in one place and the body in another place, they bring the head to the body, the words of Rabbi Eliezer. Rabbi Akiva says: [they bring] the body to the head.

(4) From what part do they measure? Rabbi Eliezer says: from the navel. Rabbi Akiva says: from the nose. Rabbi Eliezer ben Yaakov says: from the place where he was made a slain person, from the neck.

(5) The elders of Jerusalem departed and went away. The elders of that city bring “a heifer which has never been worked, which has never been yoked” (Deuteronomy 21:3). And a blemish does not disqualify it. They bring it down to a hard (eitan) wadi— “eitan” is understood in its literal sense of “hard”. Even if it is not “hard”, it is valid. They break its neck with a hatchet from behind. And its place may never be sown or tilled, but it is permitted to comb flax there and chisel rocks there.