Thanks everyone for your replies and advice. I have told my non-JW sister about it all, as she knows a police officer quite well, and she will be asking him some questions tonight. I am trying to find out if this guy has been previously reported and if he's on the sex-offenders list. If the answers are negative, I will anonymously report him. I don't know how to find out if his fiance has been told.
I can't reply to everybody, but I'd like to thank ABibleStudent/Robert for the advice given. If I were in the USA, I would undoubtedly contact Rick Simon. Unfortunately, I'm in the UK and don't think he would be able to help me out. Thanks for the PM, I will keep his details as I may just ask if there would be any point asking the questions you suggested, if that makes sense?!
Data-Dog - If I were male, I would be much more likely to confront him. And also if I weren't such a massive wuss! I am really not good at confrontation - just discussing my gas bill with someone leaves me shaking Although he is a man of small stature and I'm not a skinny woman by any means.
I will update you all once I get the answers to my questions. And then I will do whatever I need to do next. I really need to figure out how to find out if his fiance knows. I'd like to think that no woman would agree to marry such a man, no matter what the situation was, but she may be happy with a psychiatrist saying he probably won't do it again.
Mr Flipper, I so want to use your sign-off every time I end a post, because I love it. However, I'm not a thief or a plagiarist, so I shall instead wish everyone peace within (ok, ok, that is kind of stealing it - sorry!)
Take care all of you, and may whatever you believe and trust in keep you strong xx