Boyd’s Bible Dictionary:
(thief). A domesticated animal of the Weasel family used for catching rats (Lev. 11:30).
Concise Bible Dictionary:
One of the creeping things forbidden to be eaten. It is not at all certain what animal is referred to, but it is judged not to have been what is now known as the ferret. The Jews' Bible (by Leeser) has “hedgehog;” others think the “shrew-mouse;” and others the “gecko,” a wall-lizard (Lev. 11:30). The R. V. has “gecko,” and in the margin, to this and the three following names has "probably denoting four kinds of lizards."