The Wizard of Oz around here is Chad. If there's any one person who could provide you with logs and information for any legal steps you take, it would have to be him.
However, if I understand the Internet and the law properly, if this person has threatened you or your girlfriend, you have enough information to contact the authorities.
My advice is to contact your local police department and ask them who you need to contact to file a complaint (I'm not certain, but I think internet threats have been handled by the FBI, to date). I don't think they'll be able to do more than direct you to the people you need to talk to, but it's a place to start.
You might also contact AOL, as they likely have extensive abuse policies you can file a complaint through (as well, they should be able to help you block or ban the offender)