They call that "ransomware", and yes I'm familiar with it. Just wondering what name it was, but that was a dumb question since you wouldn't know because you didn't scan for it (you probably wouldn't have found anything anyway since it's not technically malware, just a browser "hijacker"). You can find out more about it here:
http://malwaretips.com/blogs/fbi-mac-os-x-virus/. As you can see from the article, it's a two second fix. It's hardly a big issue. The Windows counterpart is a pain to get rid of, but the Mac version is a minor annoyance. They're not even remotely the same thing. It's not even a virus, really (there aren't any viruses on the Mac). Alternatively you could've also used a free app cleaner tool to trash all the Safari settings. Something like this:
https://www.macupdate.com/app/mac/25276/appcleaner
I usually reformat an infected Windows PC since it's a lot easier/quicker than dealing with it. On a Mac, getting rid of malware is a relatively easy task. Fortunately though, Macs are a breeze to set up if you reformat... but I can understand where you're coming from. Clean formats are a good feeling.
🙂
The one I recommended, ClamXav, is free:
http://www.clamxav.com