the.com/crook

means A bend, hook, or curve — and by extension, someone bent on dishonesty, or the hooked staff a shepherd carries.

from From Old Norse 'krokr' meaning hook or bend, which entered English in the Middle Ages to describe anything curved — a shepherd's crook, a crook in a river. The criminal sense didn't show up until much later, in 19th-century American slang, built on the metaphor of someone 'bent' or 'crooked' in character rather than straight and honest. So the thief borrowed the shepherd's word, not the other way around.