"She claims it was some days prior, right? With some time passed, I would not expect total sadness or anger. We aren't seeing her reaction immediately after." - Sorry. I study psychology for quite some time now and I cannot agree with that. Her reaction should be the vent that she wanted from the moment the death occurred. She should've been preparing for this moment, if some days have past. Not forget about her emotions. Think about that and think how you would react in a similar situation. You will know I am right then.

Yes, I agree - it is quite doubtful. If you find more information - I welcome it. However, in my experience investigating, crisis actors usually change their identity for life and makes it impossible to track, or just really hard. Still, if you find anything, I would prompt you to share it with others.