The murderess was Charlotte Corday, I believe.
Bear with me, this ties in.  My way of visiting an art museum is unusual.  I will stride quickly from room to room (doubtless appearing a philistine) until I find one piece that "sings' to me - and then will long stay and study that one work, for half an hour or more.
I believe "The Dearth of Marat" is the title of a truly marvelous painting I thus viewed in the Louvre:  Marat lies alone, slumped in the tub with him arm limp over the side.  He is bleeding to death, and has lapsed into semi-consciousness.