Can you sue someone for writing bad things about you on facebook?

I have someone that writes under my pictures or there pictures, very rude things about me and my family. Most of the time, if it's under my pictures i can erase it, but other times i can't and it's getting out of hand. I've reported them on facebook, but that really hasn't done anything. Can i sue them for a type of slander??? even tho it's not a verbal attack? What else could i do?