Step Daughter Says She Witnessed A Shooting By Her Bio-dad

So, I am the proud stepdad of 2 kiddos. Their bio-dad hasn't been in their lives for years and is a bottom-of-the-barrel P.O.S., they call me dad and the kids are terrified of him. We are in the middle of making the divorce official as he has been avoiding our process servers and dragging his feet in every way. He has not contacted in a long time and never asks about their health and well-being but only makes random threats. It's been expensive but we are finally making progress and have a court date to finalize the divorce and hopefully get full legal custody.
That's the background, but it's not really why I'm posting. Our youngest blurted out that she had seen him shoot and kill someone and with his multiple firearm as a felon convictions, I don't really doubt it. The only hard part is that I don't know where this happened, could only really make an educated guess as to when, and the who is a complete question mark. I am also very hesitant to ask her to go back through the process of remembering because when she brought it up she just fell to pieces and ugly cried. She was shaking and you could tell it is already very hard for her. I'm proud of her for being brave and saying what was bothering her, and with her reaction I really don't think it was like, a dream or some kind of misunderstanding.
As you can tell, it's not much to go off of, and I know that we can't move forward with only her story. Without other strong evidence, there's little chance they would look into it, and I would feel like dirt if I re-traumatized her and asked her to testify or something, and then nothing happens.
Here's the question: is there a legal action here? Or do I just focus on her mental health? Should I try to include this in the divorce/custody case? Or is it just too flimsy to be brought up? I fully believe her and want to help her heal, but I'm wary of bringing this all back to the surface, especially if we get nothing good out of it.
[link] [comments]