Leviticus 5:1-2

And if any one sin, in that he heareth the voice of adjuration, he being a witness, whether he hath seen or known, if he do not utter it, then he shall bear his iniquity. Or if any one touch any unclean thing, whether it be the carcass of an unclean beast, or the carcass of unclean cattle, or the carcass of unclean creeping things, and it be hidden from him, and he be unclean, then he shall be guilty.