This article is from the Libraries FAQ, by Anthony Wilson firstname.lastname@example.org with numerous contributions by others.
Yes, and the best source of information is Marsha McCurley's
http://www.carol.net/dolphin/bibliomysteries/index.htm . Besides an
extensive bibliography, McCurley includes lists of librarian
detectives, staff victims, reference works, links to other listings,
and a collection of quotes:
"...People just don't get murdered in public libraries. It's not
done." -- Police Chief, in Murder in a Library by Charles J. Dutton