Call me skeptical when the daughter waits so long to tell about it. There’s an extreme level of proof needed before I’d take matter into my own hands, even in places like the UK where criminals have more rights than victims (unless the “victim” is an offended Muslim).
The mother may have highly suspected it for years, yet didn’t dare broach the subject,, then when it was confirmed, decided to act. He may have also been a brutal person who held his family In fear. We don’t know all the details