That's not necessarily a smoking gun; public libraries often give away old books they don't want to keep around anymore. About a quarter of the books in my pe

That's not necessarily a smoking gun; public libraries often give away old books they don't want to keep around anymore. About a quarter of the books in my personal library are ex-library books, but none were stolen. Of course if it's some popular in-demand book, it was almost certainly stolen. Most of the free library books I've scored are 50 year old textbooks about obscure/obsolete topics.