Dr. Gingerelli's Stolen Rembrandt

Carl Gingerelli is a professor of art history, an artist, and an art collector. He also gives private art lessons, and one of his students, Karen, came in to find Dr. Gingerelli lying on the floor dead. He was apparently killed as a result of someone stealing the most valuable work of art in his collection, a Rembrandt painting. If you can find out who stole the painting, you can find out who killed Carl Gingerelli.