NET
3 or when he touches human uncleanness with regard to anything by which he can become unclean, even if he did not realize it, but he has later come to know it and is guilty;
Darby
3 or if he touch the uncleanness of man, any uncleanness of him by which he is defiled, and it be hid from him, when he knoweth [it], then he is guilty.
KJV
3 Or if he touch the uncleanness of man, whatsoever uncleanness [it be] that a man shall be defiled withal, and it be hid from him; when he knoweth [of it], then he shall be guilty.