Parashas Masei · Passuk 35:33 · TT note 2
Chabad.org — English translation + Rashi
Torah Temimah points to Sotah 47b (TT note on “כִּי אִם”).
English: Our Rabbis taught: From where [do we know] that if the heifer’s neck was broken and afterward the killer was found, they do not exempt him? From “and the land shall not be atoned for the blood that was shed in it except by the blood of him who shed it.”
The eglah arufah does not free a later-discovered killer from capital liability.
Even after the ritual of the broken-necked heifer, a subsequently identified murderer is still put to death; only his blood atones for the land.