Published: Jan 23, 2013 6:18 PM EST
Updated: Jan 23, 2013 6:23 PM EST

FORT MYERS, Fla. -- Con men are finding new ways to make a fortune on credit card holders who don't bother checking their statements. It's a reminder to check your statements and if something doesn't seem right, ask questions.

U.S. Postal Inspectors showed surveillance tapes of a credit card and gift card scam that racked up more than $100,000 in losses in just one case alone.  Postal inspectors said the nationwide scam is simple and starts with stolen credit card numbers.

"We believe it was through either an online chat room where they purchased these credit card numbers or an employee at a local merchant," said David Gealey, U.S. Postal Inspector.

What happens next is the conmen go to a store that sells gift cards.  They grab several cards worth $500 each and then go to the checkout counter.  At the counter, the conmen, using your stolen credit card numbers, come up with a  phony reason why their credit card can't be swiped.

"They tell the clerk something must have happened to my card, it's damaged my dog chewed on it whatever it may be.  They would get the clerk to manually put the card number into the system. Once they did that the transaction was completed," said Gealey.

With gift cards in hand, the suspects make phone calls to transfer the money on those cards to a pre-paid debit card.

"Once they transfer those funds, they are as good as cash to them they can go to any merchant or a bank and obtain cash. In 5 - 10 minutes they obtain $2,500 in cash," said Gealey.

Postal Inspectors were able to learn the ins and outs of the scam through surveillance tapes.

"They would never actually give them the card to the clerk when they actually asked for it.  Here I'll just read you the number, they would cup the card, and the clerk is just punching in the numbers," said Gealey.

Once they discovered the scheme, postal inspectors were able to cross-check the time of the transactions with cell phone records and credit card statements to nab the conmen.

"All three of the suspects ended up pleading guilty to Access Device Fraud, one of the individuals pleads guilty to aggravated identity theft, and of all the prison terms the shortest was one year," said Gealey.

How can you avoid becoming a victim, U.S. Postal Inspectors said monitor your credit card statements and activity closely. Inspectors said very few of the victims in this case didn't even know their credit card numbers had been compromised.