Leviticus 5:3

Or if he touch the uncleanness of man, anything which caused a man to be ceremonially unclean, whatsoever uncleanness it be that a man shall be defiled withal, and it be hid from him; when he knoweth of it, that is, when he finds out about the defilement and yet omits the simple forms of purification which were provided in such cases, Leviticus 11:24; Leviticus 15:5; Numbers 19:22, then he shall be guilty, atonement should be made for the sin which he committed, for the guilt which he heaped upon himself.