I’ll likewise be at the library this weekend and will check for the book, and I have two other books in progress (with a combined ~400 pages left) so also may be a slow.
You might already know this, but 容疑者Xの献身 had a book club here, and I’ve seen @NicoleIsEnough say that the threads are left open for such a long time specifically so that people can ask questions long after the original reading times end. Also, if you come across the movie version I’d recommend not bothering with it. It wasn’t very good IMO.