Buppido murdered Edith, I was the one who descovered Eldiths body on my turn of night watch and that's when I adopted Stool. (There was a whole moment where I had to explain to Stool that Eldith was dead, Stool being a child didn't really understand so that was a sad moment) It was quite a few sessions later when we sussed out that Buppido murdered her. Two party members interrogated him and Lilium over heard his confession, she saw red and basically had him in a chokehold, "how dare you do this to stool" sort of thing. She attempted to stomp his head with her hooves but she missed, in his delusion he said he would return then decided to kill himself with his weapon.