And it shall be, that the city which is next unto the slain man, even the elders of that city shall take an heifer, which hath not been wrought with, and which hath not drawn in the yoke; (Deuteronomy 21:3)
The elders of the city nearest to the body would be held responsible for the performance of the necessary last rites. It may have been presumed that the slayer was a person from the immediate vicinity.
Heifer.
The age is not given, though Jewish commentators give two years as the age required. In other circumstances a heifer of three years is specified (Gen. 15:9).
Wrought with.
That is, not been worked as a draft animal (see Num. 19:2).