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?
I hate to say this, but do you know what he's done to rehabilitate himself? Do you know why he's allowed to work there? Have you talked to management about what you discovered?
All of your questions are very very leading. Of course we deplore rape. However, despite what you may think, we should all be given a chance to redeem ourselves.
I can understand why you fear for the safety of yourself and others around you. If you do nothing, that is entirely on you. But I do hope that you have compassion and a sense of forgiveness in your heart too. For all you know, you can also be surrounded by thieves and murderers, but none of those are publicly branded.
I urge you to bring this to the management's attention. Talk to your female coworkers and let them know.