Former Wal-Mart Stores Inc. (WMT) Vice Chairman Tom Coughlin Tuesday pleaded guilty to wire fraud and tax evasion, admitting that he stole thousands of dollars from the world's biggest retailer to upgrade his truck, pay for hunting rights and buy beer.

Coughlin, who joined Wal-Mart in 1978 and worked closely with legendary founder Sam Walton, faces up to 28 years in prison and $1.35 million in fines. Sentencing will be set at a later date.

The man who oversaw Wal-Mart's massive U.S. business pleaded guilty in U.S. District Court in Fort Smith, Arkansas, to five counts of wire fraud and one count of tax evasion.

"Today, I accepted responsibility for serious personal mistakes in judgment," Coughlin, 57, said in a statement through his attorney. "This was not an easy decision. I regret the embarrassment this matter has caused my family and friends and I thank them for their support, love and friendship."

Judge Robert Dawson ordered the 14-page plea agreement placed under seal, saying he was "concerned, deeply concerned" about pretrial publicity in the case.

Coughlin, who was released on his own recognizance, drove off in a black SUV without making further comment.

Wal-Mart accused Coughlin of misappropriating as much as $500,000 through misuse of gift cards and bogus invoices, and said he used the money to buy an odd assortment of items including customized dog kennels and a Celine Dion CD.

According to a document filed by the U.S. Attorney in Fort Smith, Coughlin pleaded guilty to a much smaller sum that includes $6,500 for his share of a private hunting lease, $2,695 for upgrades to his 1999 Ford truck, and a $200 Sam's Club gift card that he used to buy a cooler, two cases of Miller Light beer and other items.

"This whole episode has been embarrassing and painful to us as a company and as individuals," Wal-Mart spokeswoman Mona Williams said.

"Someone we expected to operate with the highest integrity let us down in a very public way," she said. "Wal-Mart has high ethical standards and the way we handled this matter makes it clear that every associate will be held to these standards with no exception."

In his statement, Coughlin called on Wal-Mart employees to "accept my decision and to continue to pull together in fulfilling Sam Walton's dream of creating the world's greatest retailer."

Shares of Wal-Mart fell 26 cents to $46.15 in afternoon trading on the New York Stock Exchange.