You searched for: “purloiner”
purloiner (s) (noun), purloiners (pl)
Someone who takes something that belongs to another person, from a store, etc.: Jillian's sister was accused of being a purloiner of books from the local book store.
A purloiner was caught trying to steal a lamp shade which she used as a hat and pretended not to know what lamp shade the police officer was talking about.