I had a teacher who refused to let any of us say “its okay” because of this exact reason.
It has taken me years to learn that it’s also okay to say “Thank you.” when someone apologizes.
It is perfectly acceptable to acknowledge that someone has apologized, and still refuse to accept their apology. There are things in this world that cannot be apologized for.
The fact that wizard law enforcement found a dude’s finger and immediately closed the investigation, declared him dead, and concluded that the only possible explanation for why they only found a finger was that he was killed so hard that the rest of him was obliterated kind of speaks volumes about why nobody followed up when the genocidal serial killer just vanished.
The Ministry of Magic is fucking useless.