Jonathan Harkness, a liquor-store regulator from Washington state, came to know “Jorge Carlos” in late 2006, when Carlos posted a Surefire flashlight for sale on eBay using a Miami street address.

Harkness bid $90, and after an exchange of e-mails on AOL, sent Carlos a money order. But the address turned out to be a private P.O. box, the high-tech flashlight never arrived, and Harkness realized he had been ripped off.

So in early 2007, he wrote his congressman, laying out his dealings with the mysterious eBay seller from South Florida and the possibility of a bigger scam. Rep. Adam Smith urged the U.S. Postal Inspection Service to investigate.

Thus began a three-year probe to unmask “Jorge Carlos,” and to figure out how many other victims he might have fleeced around the country.

The payoff: Earlier this month, Nilton Rossoni, 50, a Brazilian businessman with multiple aliases who had lived in Sunny Isles Beach and Fort Lauderdale, was sentenced to 5 ½ years in federal prison for running one of the biggest eBay scams in history.

“If [postal inspectors] had written it off, then it all would have fizzled,” Harkness told The Miami Herald.

Rossoni was convicted in October of hauling in $717,000 from more than 5,500 eBay buyers, by creating at least 260 different auction accounts, and using dozens of e-mail addresses with Yahoo, Google and AOL, as well as nearly 60 private postal boxes.

Rossoni engineered the intricate online retail scheme with the help of his son, Nilton Joel Rossoni, 28, according to an indictment. The younger Rossoni is a former Brazilian race car driver who graduated with a business administration degree from the University of Miami in 2007. He is believed to be on the lam in his native Brazil.

From 2003-08, the father auctioned thousands of products, from horse saddles to rotisserie grills, without delivering anything to the winning bidders. He maintained a legitimate reputation by fabricating positive feedback.

He also insisted that his buyers use cashiers checks or money orders, not PayPal. The anti-fraud protection services at eBay are designed to help people who only use PayPal online to purchase their merchandise.