Would you want to know? (Rape trigger?)

My sister was drugged and raped by a married couple who were friends. Because she was drugged, she blacked out. She only has flashes of memories of being in bed with both of them touching her, and woke up with bruises over her entire body, her vaginal area was worse than when I gave birth naturally. I tore. She did as well.... While we were talking about the investigation (luckily there's A LOT of evidence on her side) I asked if they confessed and said everything that happened...Would she want to know. I'm not sure if I would want to know or not. Could it help you heal? Or do you think it would make the situation worse? She already has PTSD from a previous sexual assault too. Would you want to know, if you couldn't remember? Or do you think it's best not to know?