Numbers 31:19

Purification After Battle

31:19 “Any of you who has killed anyone or touched any of the dead, remain outside the camp for seven days; purify yourselves and your captives on the third day, and on the seventh day.

Numbers 35:30

35:30 “Whoever kills any person, the murderer must be put to death by the testimony of witnesses; but one witness cannot testify against any person to cause him to be put to death.