I know he is a sex offender but is there a free way to find out what he's done?

I just found out my boyfriends uncle who he lives with went to prison my boyfriend didn't tell me why he did though. I googled his uncles name and I found out that he is a sex offender the most info I found was that he committed sexual battery. I wanna know more and the story because I may be pregnant and if so I don't want my child around him. I need a free website where I can find out more information other than him being a sex offender

The FBI's sex offender website.

http://www.fbi.gov/scams-safety/registry