How do I get rid of the FBI moneypak scam virus?

I was using Safari, and saw that one of my Open tabs and turned into an FBI warning page, which turned out to be the moneypak FBI virus scam. Has anyone else dealt with this before? And if so, how do I make certain that the Trojan is completely gone from my computer? I already reset safari, just want to be positive that they are completely gone from the hard drive.