Dozens of recorded phone calls to Stephen Mardigan in which he takes bets from gamblers, discusses how they can pay their debts and confers with other bookies offer insight into how the Portland man who now faces nearly three decades behind bars ran what federal officials are calling Maine’s largest gambling operation.

Transcripts of the phone recordings were included in documents filed Thursday in federal court in Portland that indicate the FBI also used informants, including one who lost about $2 million in bets, to build their case against Mardigan. He has pleaded guilty to operating a high-stakes sports gambling business for at least 14 years from his home on Baxter Boulevard home and his used-car business on Forest Avenue.

In two filings totaling 142 pages, federal authorities relate information gained from a cooperating defendant who collected debts for Mardigan, gamblers who lost millions in wagers and co-conspirators in the gambling operation. There are dozens of pages of transcripts of wiretaps, including one between Mardigan and his girlfriend, Patricia Nixon, in which Nixon helped Mardigan set the odds for parlay bets. The FBI said Nixon helped Mardigan by using a special type of calculator to figure out parlay bet payouts. Parlay bets are those in which gamblers bet on multiple games and win only if they win on all the games.

Mardigan, 61, pleaded guilty Wednesday to running the gambling operation for at least 14 years. He also pleaded guilty to a more serious charge of money laundering and filing a false tax return. Federal officials said he laundered about $4.5 million from 2009 to 2016 through an account associated with his used-car business and bought 30 properties in and around Portland on which he now collects about $1 million a year in rent.

He could face 28 years in prison, and will have to forfeit hundreds of thousands of dollars in cash seized by federal agents last year, give up real estate worth at least $5.6 million and pay restitution of $1.3 million under the outline of a plea deal filed Wednesday in federal court in Portland. A sentencing date has not yet been set.

WORKED WITH OTHER BOOKIES

Federal authorities believe Mardigan operated the largest gambling operation in Maine, and several of the confidential informants quoted in the filing say the same thing. Over the years he ran his operation, he took in millions of dollars in bets on college and pro football games, college and pro basketball games, hockey, golf and other sports, court filings show. The bets ranged from $30 to thousands of dollars.

The documents indicate that Mardigan worked with other bookies in Maine. He was charged under a federal law that requires at least five people to be involved in the gambling operation. So far, no one else has been formally charged, but court documents reference him working with Nixon and unnamed confidential sources, cooperating defendants and co-conspirators.

Mardigan’s biggest customer was another auto dealer, unnamed in the documents, who would send checks from his business to Mardigan’s business, Avenue Auto, to cover gambling debts.

The filing says the other car dealer paid Mardigan about $2.7 million between 2009 and 2015 to cover losses. During that period, the dealer took in about $700,000 from Mardigan for winning bets.

‘DEPRESSING TO BE OUT OF MONEY’

The money flowing between the two auto businesses looked, on the surface, to be business-to-business transactions. But during the period, Mardigan and the gambler had only about 30 transactions involving what the documents call “low-end used cars” that couldn’t account for the large sums flowing back and forth.

The documents say the car dealer placed bets with Mardigan for more than 20 years, but that he would go years without betting or refrain from betting for entire football seasons “because it was depressing to be out of money.”

The car dealer also introduced an unnamed Michigan police officer to Mardigan. The officer initially placed his bets through the car dealer, but eventually bet directly with Mardigan.

Federal agents allowed the car dealer to collect on what was apparently his last bet with Mardigan. At the beginning of the 2016-17 season, the man bet $5,000 each on two teams to win their divisions in the NFL and Mardigan paid him $16,000 on the winning bets in early 2017. The documents don’t indicate if the car dealer was allowed to keep the winnings.

FILINGS FOR FORMAL FORFEITURE

Mardigan’s second-largest customer was someone in Florida who deposited $1.4 million in the Avenue Auto account from 2009 to 2015, plus another $276,300 from associates. The Florida resident confirmed in May 2017 that all of the payments were to cover gambling debts.

The documents reveal several other aspects of the operation:

• An unnamed cooperating defendant collected debts owed to Mardigan. He said in one case, Mardigan was owed $30,000, which was negotiated down to $20,000. The man received $8,000 for collecting the debt, after which “his standing within the gambling organization rose.”

• Another co-conspirator “had a relationship with a former police officer and would kick money back to the police officer.” The police officer tipped off a co-conspirator about informants, but the document doesn’t include other information, such as where the officer worked or how much money was exchanged.

• More than $1.6 million was deposited in the Avenue Auto account in 2015, but Mardigan claimed on his tax return for the year that Avenue Auto had gross receipts of $45,000 and gross income of $5,000. Mardigan, who inherited rental properties from his father, reported rental income for the year of nearly $617,000.

There were two filings Thursday, including one titled “United States of America v. $747,046.70 in U.S. Currency (and) 10 assorted watches with an approximate value of $19,300” that represents the government’s request for a formal forfeiture of money and watches that it seized last April. The second seeks the forfeiture of 30 pieces of real estate that the federal government says Mardigan purchased with proceeds from his gambling operation. Both filings seek civil forfeiture of the money, watches and property from Mardigan. In a procedural move, that will be changed to a criminal forfeiture when he is sentenced and the civil case is dropped, officials said.

Court documents say Stephen Mardigan ran a gambling operation out of his home on Baxter Boulevard, above, and his Portland business, Avenue Auto, from 2003 to 2017. (Ben McCanna/Portland Press Herald)