One of my victims was a successful engineer from California named Tim. He first talked to one of our salesmen, who gave him the generic pitch. Then he turned him over to me to close. The first thing I said to Tim was: "Hi, Tim, this is Jim. How are you doing? Go get a pen and paper right now — I want you to write my name down." Tim immediately said, "Oh, OK, I'll be right back."

Bang. With those six words I knew that Tim was going to fall and fall hard. It wasn't just that he immediately complied with my request; it was how he complied. The tone of his voice was high-pitched and squeaky, almost submissive. It's hard to explain, but over time you pick up the nuances and subtleties in people's voices. It's the wolf sensing the lamb. He was signaling that I was in control and that he wanted me in control.

Out of the Game, for Good

All of those years I ripped people off, I knew it was wrong. But I was making so much money, I didn't care. It wasn't until those agents busted into my office in Miami that it finally hit me: What I was doing was really bad. I pleaded guilty to one count of conspiracy to commit mail fraud and went to prison for more than three years. I had a lot of time to think about my crimes. When I got out, I promised my mother I would never go back to my old ways. It wasn't easy. The first year I was out of prison I was asked almost daily to work as a closer for the latest scam. Finally, I changed my phone number so I wouldn't be tempted.

In 2009, I spoke at a Washington, D.C., fraud-prevention conference sponsored by the Federal Trade Commission. Since then, I've been working on the other side of the scam business: I shot a couple of television interviews and even did some role-playing with fraud fighters from the AARP Fraud Fighter Call Center.

Today I am 44 years old, and I live in my parents' house. I owe the federal government almost a million dollars in restitution that I don't have a prayer of paying back. Thanks to years of smoking and drug abuse, I have acute emphysema and I carry around an oxygen tank. I'm on the waiting list for a double lung transplant, but the clock is running out. Can you spell karma?

People sometimes ask me about remorse. I do understand that innocent people got hurt as a result of my actions. I think about my victims. I pray for my victims. And even though I have spent the past four years trying to help people avoid monsters like me, I wonder if it has been enough.

Jim was convicted on charges of conspiracy to commit mail fraud in 2006. Doug Shadel, a former fraud investigator for Washington state's attorney general's office, is the author of Outsmarting the Scam Artists: How to Protect Yourself From the Most Clever Cons (AARP/Wiley); he is also currently AARP Washington's state director.