A Portland man has pleaded guilty to running a high-stakes gambling operation from his home and used-car business for 14 years.

The charges and plea agreement for Stephen Mardigan, 61, of Portland were entered in federal court Wednesday morning.

Federal officials seized nearly $750,000 from Mardigan, as well as cash and jewelry from others they allege were involved in the gambling operation, during raids on April 7, 2017. But he wasn’t charged until papers were filed in the plea agreement Wednesday.

The court documents say he will plead guilty to unlawful gambling, money laundering and filing a false tax report. He could face up to 28 years in prison.

Under the plea agreement, Mardigan will go to jail for a still-to-be-determined period, forfeit most of the money that was seized, pay restitution of more than $1.3 million and forfeit real estate worth nearly $5.6 million that he bought as part of the money-laundering scheme. Officials said he could have to pay back twice whatever he gained from the gambling and laundering operations.

According to court filings, Mardigan has admitted to running an illegal gambling operation out of his home on Baxter Boulevard and his Portland business, Avenue Auto, from 2003 to 2017. He took bets on college and pro basketball games, college and pro football, baseball, professional hockey, stock car racing and golf tournaments. The filing says bets typically ranged from $30 to $10,000, but transactions with two gamblers totaled nearly $5 million.

Donald Clark, an assistant U.S. attorney and spokesman for the U.S. Attorney’s Office in Portland, said he is not aware of a larger gambling-related case in Maine in terms of the length of the operation and the total amount wagered.

Beginning in March 2017, FBI agents wiretapped two phones on which Mardigan accepted bets, the document said.

According to court filings, Mardigan operated his gambling business primarily from Avenue Auto, a used-car business on Forest Avenue. From July 2008 to June 2016, Avenue Auto reported only 57 sales, but Mardigan deposited more than $11.3 million in Avenue Auto accounts, according to the court documents.

One bettor, the files say, wrote checks from his auto business to Avenue Auto for nearly $3.1 million. Another gambler, according to the documents, wrote checks for more than $1.4 million to Avenue Auto, along with $200,000, apparently in cash, from that gambler’s associates. It wasn’t clear Wednesday whether other people would be charged in the case.

The government’s synopsis of its case against Mardigan also said that he laundered some of his gambling winnings by buying property, including real estate and houses in Cape Elizabeth, Westbrook, Gorham and Portland. The 19 properties range in value from roughly $31,000 for a lot on Forest Avenue to $985,000 for his home on Baxter Boulevard in Portland. The three Cape Elizabeth properties, all homes on Tides Edge Road, had a combined value of nearly $1.5 million.

The document doesn’t provide specifics on the false tax return charge other than to say Mardigan failed to report his income from gambling.

The illegal gambling charge carries a penalty of up to five years in prison and a fine of up to $250,000; money laundering can be punished by up to 20 years in prison and a fine of up to $500,000; and the false tax return charge can be punished by up to three years in jail and a $100,000 fine.

The plea agreement says the government won’t seek a sentence beyond the low end of the federal sentencing guideline ranges, which are calculated on a range of factors, such as a defendant’s prior record. The guideline range is calculated by the judge handling the case and likely will be decreased from the maximum because Mardigan agreed to plead guilty and accept responsibility for the crimes.

The Baxter Boulevard home of Stephen Mardigan, 61, of Portland who pleaded guilty to running a high-stakes gambling operation from this location. Ben McCanna/Portland Press Herald)

Copy the Story Link