I was watching a Crime channel show called 'The Mind of a Murderer' on the ID channel (Investigation Discovery):
...and though sometimes hard to watch (it's not excessively graphic, just heart-rending), it shows how much the 'victim' is almost a passive or even active participant, because they seem to ignore all danger signals and keep going back to their abusers.
One show was horrific and because of a "failure" of 911 (blamed on a shift change, of all things) the victim, though transmitting to 911 as she was being killed, was stomped to death.
She went back to this guy with 'explosive mood disorder' (according to the show) five times, I think. She ignored death threats, beatings, slapping, having bottles thrown at her and kept telling the cops she loved this guy.
I'm not saying your case is the same AT ALL. I'm just suggesting that in hindsight these things look totally preventable, but nothing seems to get done. The police were even sitting in the room when he called and made death threats. The lead investigator quit and retired because of this (I think because he did nothing, drug his feet or laughed it off, IDK).
Just something to think about. Fails all around and then it happens, despite 'orders', alarms, 911, cops' knowledge, because the most important person didn't 'wake up' and realize the real danger they were in.