Still sounds like speculation and social media rumour to me. I'm sorry for her loss, but this doesn't prove anything, especially not any kind of action or inaction D would have to answer for.
I agree ,if sister in law did state that, IMO it is grief speaking when faced with a crime your mind and body shuts down you can even say what people regret later yet people will bring it up in a way of " How could you say something so heartless", ie Hoddle Street Massacre, Melbourne ,Australia 9th August 1987, the poor Petrol Assistant Girl staggers in to the shop in total shop, she gasps out "There is someone shooting,......dead bodies everywhere...... Do you still want me to serve petrol?"
When you been in the same situation as the house mate, which I confess ( I am not trying to jump on the bandwagon) but I been like other people in the same situation and been silent, but it took me over thirty years to speak up, I now reported it, it was witnessed, and action was taken. I hope the girl found justice and peace.
I was being interveiwed in regards to a children home I lived in when I was 11 years old, about a certain few House Parents. one of them they were enquiring information regarding a woman , I would just call her" L " during the interveiw I suddenly recalled the "Incidient" first time after so many before and blurted it all out. At the time I had no understanding what had happened it was all just sound but it terrifed me. Years before in the home a teenager was brought in after midnight, put in a room on her own just down the hallway from my room I was awake as I could not sleep, short while later we had the hourly room check, our room doors was nearly clear glass pane they would shine a torch through. Around the same time, I could hear muffled cries, whimpering sounds from her room. I decided to go to the girl, as I stepped into the hallway I noticed her door was open, I could hear L voice inside her room as she was mocking the girl ( words could not hear clearly) I went back in my room, L stormed out shinning torches in all rooms goes back into girls room ,there was some noises then the girl room door slams shut. L walks past my room back to Office, short later, another house parent does room check, room oppisite,,My room then girls room, then I hear House parent scream, runs up hallway, two house parents minus L rush down, they speak comforting words as they carry the girl past my room( I can see as my bed faces the door) girl moaning in pain. Seconds later L is clearing /cleaning the girl room as she drags linen/mattress out she checks all rooms, when the other House Parent comes down L claims she is distressed and unwell she going home could the other House Parent look after everything until the other House Parent gets back from the Hospital. There was four girls and myself in those room, even the House Parent "woke" me up to see if I was Okay, even the other we said none thing about what happened earlier. L was away for a few days, Myself and other children never spoke a word, did not talk to each other. I think, hearing more than seeing can affect so much of a human mind and well being, and I can understand how IMO it can affect the house mates to the point it can be blotted from their mind, even the action of few hours later on why their housemates werent up, why they did not want to check fear of what has happened speaks of them still in shock, you don't want too so delay the horrible truth. IMO. May she and other house mate should not be question about their actions but be given understanding, grief makes you lash out but not at innocent parties.