How does employing a rapist not constitute an unsafe work environment for female employees?

So I just discovered that I have been working next to the waste of oxygen that raped my best friend several years ago. I work in a manufacturing environment and I know that you can't fire someone just for being a sex offender unless it directly interferes with work duties (in the US). But despite it being a primarily male workforce he does work with several women who have no idea what he is. He literally followed a woman home, broke into her house, and raped her. Him working here puts every female employee at risk. How is that not an unsafe working environment? How is it at even legal to employ him anywhere where he will have contact with women?