There were three suspects: Pismo, who has a track record of theft, Janet, and Syke
The main clue is that it was very cold in the library. Syke was seen wearing a ski jacket just to go in and pick up her book. And yet Pismo said he saw Janet leaving while carrying her jacket. That's odd, unless she was hiding something beneath it!
Janet took the book. When Runt confronted her, she said, "It has those beautiful gems on it, I just wanted to touch them for a while. I was going to bring it back!"
* Half credit given if you guessed Dr. Pravus, because he's so evil he's usually a good guess.
Who stole Uncle Ludwig's book? Solution:
Who stole Darthin's hand? Solution: