Principle
Under the Law of Moses, testimony from at least two witnesses was required to put someone to death.
Explanation
An Israelite could not be put to death simply on the testimony of one witness. Two or more were required:
6 Whoever is deserving of death shall be put to death on the testimony of two or three witnesses; he shall not be put to death on the testimony of one witness. 7 The hand of the witnesses shall be the first against him to put him to death, and afterward the hand of all the people.
(Deuteronomy 17:6-7a OSB)
We should note that the broader context of these instructions was an Israelite committing idolatry:
1 “You shall not sacrifice to the Lord your God a young bull or sheep having any blemish or defect, for that is an abomination to the Lord your God.
2 “If there is found among you, within any of your cities the Lord your God gives you, a man or a woman who does evil before the Lord your God in transgressing His covenant, 3 and who went and served and worshiped different gods, either the sun, moon, or any ornamentation of heaven, which He did not command, 4 and it is told you, then you shall inquire diligently; and if it is indeed true that such an abomination happened in Israel, 5 then you shall bring out that man or woman; and you shall stone to death that man or woman with stones. 6 Whoever is deserving of death shall be put to death on the testimony of two or three witnesses; he shall not be put to death on the testimony of one witness. 7 The hand of the witnesses shall be the first against him to put him to death, and afterward the hand of all the people. So you shall put away their evil from among you.
(Deuteronomy 17:1-7 OSB)
