Experts Warn: Lose Weight, Not Cash

"It's unethical," Kroll said. "There should be no requirement for any up-front payment."

John Mullikin, who the Colorado Department of Corrections said has been convicted of theft four...

John Mullikin, who the Colorado Department of Corrections said has been convicted of theft four times, is suspected to be behind a Web site that promises participants in a weight-loss study a monthly check for $300 in exchange for taking diet pills. Women who sent in the required $144 deposit to participate never received their checks, they said.

(ABC News)

Colorado state records show the weight loss drug study is based in a Denver apartment in the name of John Mullikin, the same man the Better Business Bureau said is the so-called "researcher" behind the DBL-824 "study."

Mullikin has at least four convictions for theft, according to the Colorado Department of Corrections.

"He's out there somewhere," Liehe said. "He just doesn't want to hear from us."

Mullikin may be at it again. There's a new study for a weight loss drug called Evaril II. It also uses a Denver P.O. box, asks for a $150 deposit and promises $1,000 for participants.

And the study is based in that same apartment.

"This Web site is certainly deserving of investigation by either the Federal Trade Commission, the Food and Drug Administration or both," Kroll said.

But Pech said she won't ever again be a victim. She learned her lesson when it comes to weight loss.

"I'm going the little bit harder route … diet and exercise this time," she said.

Mullikin did not respond to "Good Morning America's" requests for comment.

His drug studies use some names very similar to those of real companies with absolutely no connection to his operations.

No one seems to know what was inside the pills sent to people who enrolled in the program. But "GMA" has not heard of any health complaints from anyone who participated in the weight loss study.

In response to our inquiries, the FDA said it is looking into the supposed diet studies.

The Denver Better Business Bureau said when you cut away all the fancy Web stuff, this is just like a work-at-home scam. If you're asked to pay money to make money, watch out, the organization said.