A Sanford man quickly entered a guilty plea Friday after he was charged the day before with scamming shipping companies he used to illegally ship alligators out of hundreds of thousands of dollars.

Joseph Krefetz was charged Thursday with using fraudulent credit cards to pay for shipping and illegally selling wildlife, according to court records.

Investigators said Krefetz came to their attention in 2012 when he filed a police report about a customer in Chesapeake, Virginia, who used a fake credit card to pay for an alligator.

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When police looked at the shipping invoice from the transaction, they found “fictitious sender information” and that he had paid with a fake credit card, his plea agreement filed in Orlando federal court said.

“Further investigation revealed that Krefetz had discovered a loophole in the FedEx and UPS shipping systems that allowed him to ship packages by dropping the packages off with packing slips which referenced fabricated credit card information,” the plea agreement said.

By the time the companies realized the payment information was fake, the packages had already been shipped, investigators said.

To keep the scam going, he would change the sender information to keep the shipping companies from catching on, court documents said.

FedEx estimated Krefetz was able avoid $164,207 in shipping charges via the scam; UPS estimated it had lost $142,316, investigators said.

As part of the investigation, agents with the U.S. Fish and Wildlife Service and Florida Fish and Wildlife Conservation Commission intercepted four packages shipped by Krefetz, court documents said.

All four were being shipped to different addresses outside of Florida, with three containing baby American alligators and one containing a dwarf caiman.

When agents with the U.S. Fish and Wildlife Service and U.S. Secret Service raided his business, JP Pets in Sanford, they reported finding thousands of FedEx packing slips and hundreds of UPS slips that were filled out using nearly 300 fake credit and debit card numbers.

On the charges of access device fraud and transportation of illegally possessed wildlife, Krefetz faces a maximum prison sentence of 15 years and fines of $270,000.