Leviticus 5:2, 3

“ ‘If anyone becomes aware that they are guilty—if they unwittingly touch anything ceremonially unclean (whether the carcass of an unclean animal, wild or domestic, or of any unclean creature that moves along the ground) and they are unaware that they have become unclean, but then they come to realize their guilt

or if they touch human uncleanness (anything that would make them unclean) even though they are unaware of it, but then they learn of it and realize their guilt