Charles Ellicott Commentary Exodus 21:29

"But if the ox was wont to gore in time past, and it hath been testified to its owner, and he hath not kept it in, but it hath killed a man or a woman, the ox shall be stoned, and its owner also shall be put to death." — Exodus 21:29 (ASV)

His owner also shall be put to death. —It seems clear that under this law the representatives of the slain person might have exacted life for life; but probably they would in almost all cases have been ready to accept a compensation.