TT #379 · Parashas Shoftim · Seventh Aliyah · Passuk 21:06
And all the elders of that city who are nearest to the slain person shall wash their hands over the heifer whose neck was broken in the valley.
Torah Temimah points to Sifrei Devarim 209.
TT lemma: הַקְּרֹבִים אֶל הֶחָלָל.
English: ‘Who are nearest to the slain person’ – those who are the nearest.
Derash confirming the identity of the elders (Sifrei) — the same group that was charged by the measurement.
The elders who wash are those of the city that the measurement identified as nearest to the body.