He scammed $1.8 million from women he met online! How to protect yourself.

The dating game is increasingly played online. According to a study from the Pew Research Center, nearly 36 million Americans — roughly 15 percent of the adult population — have used an online dating site or mobile app, compared with just 3 percent a decade ago.

Of those who have used the technology, 80 percent say it is a good way to meet people. But unlike other computer games, the risks in online dating are not just virtual.

"You're dealing with total strangers, and so I think that's one of the reasons that it's ripe for potential fraud," Arizona Assistant Attorney General Scott Blake told CNBC's "American Greed."

Consider the case of serial grifter Daylon Pierce, now serving a 15-year prison sentence for fraud after he used online dating sites as hunting grounds for scam victims. He conned 13 women out of around $1.8 million in various frauds between 2013 and 2016.

"I'm guilty," Pierce told "American Greed" in an exclusive telephone interview from the Red Rock Correctional Center in Eloy, Arizona, where he is serving his time. "I sit here and think about everything that I've done wrong, and it's millions of dollars that people's lost. You know it's my fault. I take the responsibility, and I got to live with it."

One of the women — "Gina," who spoke to "America Greed" on the condition that her real name would not be used — says Pierce was a charmer alright. But his real modus operandi eventually became clear.

"Suck the life out of us victims. Take us for whatever you can, and fast. That's what he did," she said.

Of course, the successful, happy, fraud-free relationships begun online far outweigh the bad ones. But online dating expert Julie Spira, author of "The Perils of Cyber-Dating," says these days, you cannot be too careful.

"It's not that sexy and romantic to do a background check, but some of the things that you can find that are revealed are maybe lawsuits, judgments, even an alias on someone if they're pretending to be someone else," she told "American Greed."

Beyond Google

Googling your potential partner is a start, but in this day and age, it is not nearly enough. Fortunately, people love to share all kinds of information about themselves on social media.

"You should really look at social media as being your wing man and your new best friend," Spira said.

You can go to LinkedIn to view the person's work history. (Don't forget to check out the companies to make sure they are real.) Go to Facebook to learn their relationship status and find out about their family and friends. Get clues about their likes and dislikes via Twitter and Instagram.

Of course, anyone can create a fake persona on social media, so do not stop there. Spira says to pay careful attention to the photos that your potential squeeze posts online.

"If they're not updated frequently; if they happen to be stock photos or somebody's posting photos at very fancy places, in front of Ferraris — most people don't do that if they have money," she said.

To determine if that Instagram image is really just a stock photo, run it through a Google reverse image search. Another site, TinEye, will show you every place on the internet where a particular photo appears, and will even let you track where they show up in the future.

"This way you can see if they're anywhere around the world, and if they're actually really a model from Italy as compared to a stockbroker from San Francisco," Spira said.

And if your potential partner says he or she is a stockbroker, or an attorney, or any number of professions whose practitioners must register somewhere, that is another avenue to check.

"Go to the state bar association website — that's free — and see if they're a practicing attorney and if their license is valid," Spira said. "Do the same thing if they're a doctor — go to the medical boards. If they're in real estate, find out if they have an active real estate license. A lot of these little search tips are free and they're really worth your time."

And as difficult as this might be to consider, go to the National Sex Offender Public Website to make certain the person is not in the registry. Fortunately, most of the large, reputable dating sites such as eHarmony and Match.com will already do that for you.

"Any site that has a large number of members really has systems in place" and checks its prospective members before allowing them to post profiles, Spira said.

You swiped right. Now what?

After you have made a connection with a potential suitor, some of the real work begins. After all, this is where con artists like Pierce put their schemes into action.

Gina had found Pierce online in 2015. She was recently divorced, looking to make a fresh start, and Pierce seemed to say all the right things.

"He was someone I was attracted to," she recalled. "He had a real long profile, and you're like, yeah, yeah, sure, sure, you know, 'walks on the beach' kind of thing. But I did agree to meet him."

Pierce had claimed to be an investment professional, and within days offered to help her maximize her $94,000 divorce settlement. Gina says she balked at first, but Pierce skillfully shamed her into turning over the money.

Pierce's own defense attorney, Chris Doran, said that was what his client did best.

"Daylon could sell someone a nickel for a dollar," he said.

In the world of online dating, con artists have the added benefit of their potential victims being eager — and in many cases desperate — to make a connection. A crook will exploit that every time.

"So if you like football, they like football. You like Coldplay, they like Coldplay. Whatever you like. You feel so excited that somebody gets you," Spira said. "That's their goal. They want to hook you in to grab your heart and potentially grab your wallet."

To protect yourself, take your time before meeting that special someone in person for the first time, or even communicating by e-mail or any means other than the dating site where you met.

"Until you feel really comfortable, use the dating sites because they're a good place to really keep the conversations and a record of the conversations going," Spira said.

As you start to feel more comfortable, you might talk to the person on the phone or in a video conference. When you finally meet in person, do so in a public place. And continue keeping your guard up.

"Never talk about money. Never talk about your inheritance or a windfall," Spira said. "Don't let them know your exact address of where you live or where you work."

And whatever you do, keep your wits about you.

"I also recommend not drinking on a date," Spira said. "Drink dates are so popular, but go ahead and order a mocktail instead of a cocktail to make sure that your judgment isn't impaired."

Slow and steady

Of course, the whole point of dating—online or otherwise—is usually to find someone with whom you can let your guard down and be completely open. So it is important to not get carried away.

"If you tell your date, 'Wow, I just checked you out and I saw that picture of the wedding you went to last night,' it's going to sound creepy and don't be surprised if they cancel the date," Spira said. "So, do a little bit of searching, and if things look like they actually match up, don't get obsessed with it. Don't keep doing it. You don't want to seem like you're this huge cyberdetective and that you're stalking someone, because it takes the fun out of meeting someone."

But keep in mind that just like the olden days when people met in bars or at parties or other social functions, dating can be a minefield littered with creeps. Yet with a little bit of care, you can sidestep the Daylon Pierces of the world and find Mr. or Ms. Right.

See more exploits of this "Con man Casanova," and how Daylon Pierce's victims finally come together to help bring his party to an end. Watch an ALL NEW episode of "American Greed" , Monday, Sept. 3, at 10 p.m. ET/PT only on CNBC.