That's a tough one. People who are arrested for something as innocent as public nudity can be charged as a sex offender and carry that stigma for the rest of their lives. My opinion is that our laws concerning sex are WAY too strict.
Find out the true details of the offence -- if you find it discusting tell him/her to **** off
They're not your real friend if they haven't told you, especially if you knew them for years
I would want to know what the offense was. There are a lot of things I consider harmless that can get you on that list. Some places having consensual sex with a 17 year old when you are 18 still gets you on the same list as rape or child molestation. It would be important to know the specifics.
Beyond that it is hard for me to say. People can and do change, but it is very rare. Obviously if they were acting creepy towards you they wouldn't still be a friend. But it wouldn't be wise to let a ********* babysit, no matter how good a friend they were.
I don't think I would be too happy about it, but if he/she is a true friend I would at least find out the circumstances before condemning them. If it had anything to do with kids, or was a rape, that's not cool and would probaly have to walk away. I guess I really couldn't say though until I was in the circumstance.