(CNN) -- Postal authorities say a Michigan postal worker has admitted to stealing some $20,000 worth of first-class stamps since September and trying to sell them to online auction-site customers to help pay his mortgage.

An arrest warrant has been issued for John Auito, 42, of Macomb, Michigan. Auito, a postal employee since 2003, resigned after investigators confronted him on April 30.

He has made arrangements to turn himself in, authorities said.

Deputy Special Agent-in-Charge Breck Nowlin of the USPS Office of the Inspector General told CNN that Auito has admitted to stealing stamps that were being shipped to retail stores, and he said he used the money from selling them to make delinquent mortgage payments.

Nowlin said Auito was contacting customers of the online auction site eBay, and offering to sell them stolen stamps at below-retail prices.

A call from CNN to a listing in Macomb, Michigan, for John Auito was not answered.



CNN's Melissa Roberts contributed to this report.

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