If you haven’t heard yet, there are some super creepos out there on the web—and not just the Craigslist killer, either. Plenty of whack jobs take up residence on dating sites, just waiting for one of the 25 million sweet single young things who search for love online every year to declare that they must love dogs and profess their undying love in a canoe—and then take advantage of them, rape them, and even kill them.

Jeffrey Marsalis was one such sicko-path. Known as “the Match.com serial rapist,” this monster—who egotistically proclaimed himself a surgeon, an astronaut, and a CIA agent, among other things, on the dating site—who drugged and raped 21 women in Philadelphia.

Apparently, Marsalis made himself look like a rich, accomplished god among men, ensnaring women with pictures of himself in scrubs and astronaut gear no less, and charming them into a real, live date. After meeting the good doctor, his dates would suddenly wake up in his bed, not able to remember what had happened or how they’d ended up there—all victims of being drugged and date-raped.

Up until this year, he’s even walked away from all of these crimes, found not guilty on ten charges of rape. Finally, this past April, he was charged of rape yet again—this time, in Idaho—and unlike the other women who were left wondering what the hell had happened, this victim was certain she had been raped; after all, she was a lesbian.

She went right to the cops, had a rape kit done, and also had a witness—a cab driver who testified to seeing Marsalis dragging her to his place. So now, eight years later, he’s finally been sent to prison on rape charges.

Marsalis, of course, says he’s innocent. “Let me make something very, very clear to you. I have never drugged anybody. I have never raped anybody. I have never forced myself on anybody. Ever.”

Let us make something clear to you, little creep: the guy in prison who breaks you in will say the same thing.

While 120,000 online matches end up in marriages, it’s important to remember that you can’t simply trust someone because they’re using the same dating site you are. “Dr. Jeff” here was obviously able to lie about whatever he very well chose—just as you can, I can, and anyone else can when they’re posting about themselves online.

A story like this could happen to any woman, anywhere. Be cautious when you give out your information online, and err on the side of caution—give only your first name if you aren’t comfortable with any other information. Beware free dating sites, especially ones that don’t have background checks. If and when you agree to meet someone you’ve never met for a date, be sure to do it with someone you know present in a public place, taking separate vehicles—and never accept a drink when you don’t know where it came from.