If anyone kills a person, the murderer is to be put to death on the testimony of the witnesses. But no one is to be put to death based on the testimony of a lone witness.

Matthew 18:16
But if he will not listen, take one or two others along, so that 'every matter may be established by the testimony of two or three witnesses.'

John 7:51
"Does our law convict a man without first hearing from him to determine what he has done?"

John 8:17
Even in your own Law it is written that the testimony of two men is valid.

John 8:18
I am One who testifies about Myself, and the Father, who sent Me, also testifies about Me."

Exodus 21:12
Whoever strikes and kills a man must surely be put to death.

Leviticus 24:17
And if a man takes the life of anyone else, he must surely be put to death.

Numbers 35:16
If, however, anyone strikes a person with an iron object and kills him, he is a murderer; the murderer must surely be put to death.

Numbers 35:31
You are not to accept a ransom for the life of a murderer who deserves to die; he must surely be put to death.

Deuteronomy 17:6
On the testimony of two or three witnesses a man shall be put to death, but he shall not be executed on the testimony of a lone witness.

Deuteronomy 19:15
A lone witness is not sufficient to establish any wrongdoing or sin against a man, regardless of what offense he may have committed. A matter must be established by the testimony of two or three witnesses.

Deuteronomy 27:24
Cursed is he who strikes down his neighbor in secret.' And let all the people say, 'Amen!'

Whoever kills any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.