Arcana Coelestia # 9153
9153. 'If the thief is not caught' means, if there is no recollection of what has been taken away. This is clear from the meaning of 'if the thief is caught' as, if there is a recollection of what has been taken away, dealt with just above in 9151, at this point no recollection of it since it says 'if he is not caught'.
Numbers 3:10
10
You shall appoint Aaron and his sons, and they shall keep their priesthood. The stranger who comes near shall be put to death."