A discerning thief broke into a Chester County bookstore over the weekend and made off with some rare and valuable books, authorities said.

Among the items stolen was a Franklin Press limited edition of To Kill a Mockingbird, valued at $150, said Fred Dannaway, assistant manager at Baldwin’s Book Barn.

The thief took at least 20 books from a case in the front of the store on Lenape Road in East Bradford Township, Dannaway said.

“It was apparent they knew what they wanted," he said. Oddly, he added, the burglar didn’t touch any money in the register and left behind some expensive books displayed on a center counter.

The thief struck with precision, likely under cover of darkness. When Dannaway arrived to open the rare book store on Sunday morning, he found the front door window shattered and the inside lock unlatched.

Store employees, along with West Chester police, are working to determine all that was stolen. Dannaway said the store doesn’t have a catalog of its inventory, which includes more than 200,000 used and rare books, as well as art and antiques.

In the 17 years he has worked at the store, Dannaway said, it had never been burglarized, although people have tried to shoplift.

The five-story barn and storefront used to have a motion-activated security system, but it has been turned off for a while because the store’s cats were regularly setting it off, Dannaway said. Now, the owners have plans to bolster security, he said.

Built in 1822 as a milking house, the barn became home to a collection of rare books and collectibles in 1946, when Lilla and William Baldwin moved their store there from Wilmington. For a time, it included a country store museum.

The book barn has been featured on C-SPAN and Good Morning America, and in other national media.