Rashi on Deuteronomy 21:2/רש"י על דברים כ״א:ב׳

1ויצאו זקניך THEN THE ELDERS [AND THE JUDGES] SHALL GO FORTH — i.e. the distinguished amongst thy elders, these are the Great Sanhedrin (Sotah 44b).

2ומדדו AND THEY SHALL MEASURE — from the place where the corpse lies,

3אל הערים אשר סביבת החלל UNTO THE CITIES WHICH ARE ROUND ABOUT HIM THAT IS SLAIN — in every direction, in order to ascertain which is the nearest.