This is an oldish case, and the book thieves were caught. But this is from their appeal:
“The defendants were college buddies (19-20 years old) who hatched a plan to steal rare books from the special collections library at Transylvania University (Lexington, KY) and sell them at auction in New York City. …
In July 2004, after months of idle discussion, these four men decided in earnest to carry out the robbery, which led to months of research (about rare books, auction houses, Swiss Bank accounts, etc.), brainstorming, and planning. The plan involved only certain, rare and very valuable books….
…the robbery was finally at hand and after months of planning, this was the plan: all four men would enter the library, take the books by force, and run for it. They arrived at the library dressed as “old men” — makeup, wigs, hats, and costumes, such as “one would typically see worn in a play or some other type of theatrical performance” …..The costumes were sufficiently ridiculous that two library employees, including Susan Brown, the Director of the Library, noticed them, but merely assumed some sort of college prank or goof…
…Mrs. Gooch had begun to free herself to call for help. She yelled to Susan Brown that they were being robbed, and Ms. Brown wheeled around to pursue the robbers. She caught up to them in a stairwell where they were attempting to open the emergency exit and, surprised by her arrival and aggressive confrontation, they dropped several objects — specifically, the two remaining volumes of the Birds of North America four-volume set…”
The rest of it is quite entertaining if you want to read the full case
But the best bit on page 4 is:
“Once the robbers had escaped, the police were called, but before the police could document the crime scene, some librarians collected the discarded objects and returned them to their proper places.”