They had a child together, but she had moved on and was dating (and planning to marry) another man. He and his buddies, while on duty, stalked her incessantly. He once pulled a gun on her and then put it to his head in front of their 3 year old daughter. He routinely broke into her home, both while she was there and when she was not. He would drive through the parking lot at work, lurk outside...watching her through the window.
She complained to his supervisors and it did nothing but to escalate the situation. And yes, he was violent towards her....not to the kid as far as I know.
Thankfully, once she got married (and “someone” finally called his wife), it stopped. He had at least 10-20 people in his department participating in this harassment..she went nowhere without being followed...sometimes by two or more of them....and it went on for over two years.
Sadly, the scenario you describe is far too common-—and the just-us department turns a blind eye to it.