As State Police trooper after trooper filed into court this year to face fraud or misconduct charges, they’ve had one staunch defender on their side.

Passionate, profane, and often pugnacious, longtime union boss Dana Pullman has downplayed trooper wrongdoing, chiding politicians and blaming State Police officials for fostering a culture of corruption.

“Where’s the accountability at the top?” Pullman has asked repeatedly.

But now the tables have turned on Pullman, a towering man who — until recently — had near total control of the powerful union. He’s at the center of his own federal fraud investigation, with investigators asking whether the union leader was helping himself while helping others.

Agents from the FBI and IRS are poring over the financial records of the 1,900-person union, including documents related to millions of dollars in revenue and assets that Pullman alone had access to, according to one person with direct knowledge.

Investigators are trying to determine whether Pullman financed a lavish personal lifestyle on the union’s dime, spending tens of thousands of dollars on expensive restaurants like Morton’s, Mooo, and Abe & Louie’s, and a fully equipped $70,000 Chevy Suburban, the person said.

Pullman, who resigned from the union in late September, continues to earn an annual trooper’s salary of $91,000. He had been earning an additional $71,000 from the union.

What began this summer as a federal probe into whether the union reimbursed its board members for political donations has expanded in recent months to a wide-ranging look into possible malfeasance by Pullman or other union leaders, as well as a review of an associated nonprofit fund that benefits law enforcement officers and their families, according to the person with direct knowledge.

Pullman, 57, referred questions to his lawyer, Martin G. Weinberg, who called him “an indefatigable union leader.”

“He elevated this union, advocating for his members and vigorously and tirelessly fighting for their interests,” Weinberg said. “We’re optimistic that when any current investigation concludes [authorities] will share that view.”

With Pullman at the helm for the last six years, the State Police Association of Massachusetts, or SPAM, became more powerful on Beacon Hill than ever before. Many sought his support and few wanted to cross him.

“He inherited a vibrant organization,” said one former state representative who spoke on condition of anonymity for fear of angering the union. “But Dana is a larger-than-life figure — a big boisterous dude who threw his weight around. He made himself a Trumpian figure. And the more he threw his weight around, the more folklorish he became. And a lot of people hated him for it.”

Retired State Police major Dennis Galvin said the union’s aggressive lobbying under Pullman and donations to state lawmakers have enhanced its clout.

“There’s not too many lawmakers that don’t want to tap into that,” said Galvin, president of the Massachusetts Association for Professional Law Enforcement, a police advocacy group.

Of nearly a dozen current and former municipal police officials contacted by the Globe, none wanted to comment on the influence of the State Police force or its union.

Besides instilling fear in some, Pullman also inspired loyalty. There were few people he wouldn’t do favors for. He took calls in the middle of the night from anguished troopers under investigation. He serves on the board of the Greg Hill Foundation, created by a Worcester radio disc jockey that provides funds to families touched by tragedy. And his nonstop, profanity-laced rants made him as entertaining as he was forbidding.

The upheaval at SPAM occurs as State Police rank-and-file are being scrutinized like never before, facing internal audits as well as state and federal criminal investigations.

The new union president, Sergeant Mark Lynch, has already been questioned by federal investigators, and several members of the executive board are expected to cooperate with prosecutors, according to one person with direct knowledge.

Investigators are looking at expenses Pullman charged to a union debit card that had no limit, according to two people with direct knowledge.

Pullman, who served as union treasurer from 2008 to 2012, could also request expense reimbursement checks from the union without providing receipts or documentation, one of the people said.

Compounding the potential problems is the fact that the union destroyed three years of financial records during an office renovation earlier this year, that person said.

Federal investigators have also subpoenaed records of the Pullman Brothers Family Foundation, a nonprofit run by Pullman’s wife, which raises money for sick children.

Pullman, who declined to comment, has previously denied any wrongdoing involving the foundation.

More recently, investigators have asked about the SPAM Benevolent Fund, a charity that gives scholarships and grants to first responders and their families, according to the person with direct knowledge. A black tie $500-a-ticket gala at the Renaissance Hotel in the Seaport last November raised more than a million dollars — including hundreds of thousands of dollars for sought-after “Protect and Serve” SPAM license plates with low numbers.

Pullman’s attorney, Weinberg, said his client single-handedly turned the benevolent fund into a well-respected, well-funded charity.

As a trooper, Pullman, who joined the force in 1987, rarely made news — except in 1994 when he and other members of the violent fugitive arrest unit captured three prison escapees in a New Bedford housing development.

In 2008, he began serving as union treasurer and his profile grew when he became president in 2012.

This year, he’s been omnipresent as trooper payroll fraud cases dominate the headlines. But he, too, was once investigated for inflating his pay. He was accused in 2006 of brokering deals with construction companies to overpay on private details. He received a five-day suspension and acknowledged exceeding hour limits, but denied brokering deals.

Since resigning from the union’s leadership, Pullman was reassigned to Troop C in Holden. He is currently not working, but using accrued time, said State Police spokesman David Procopio.

Financial records show that the union has been running a deficit for several years under Pullman.

The union collects nearly $2 million a year in dues, according to the nonprofit’s tax filings. It reports another $2 million in an investment account.

In 2016, it collected $2.3 million in revenue, including $1.9 million in member dues, yet ran a $48,000 deficit, filings show.

The union reported paying out $522,143 in grants to retired members or relatives of fallen troopers — less than the $594,083 paid in salaries to union officials.

It’s unclear how much care went into the tax returns, which are rife with misspellings, including Pullman’s own name. Basic terms are misspelled — “bagaining,” “arbiration,” and “diliberation” — and repeated year after year.

Elizabeth Keating, a Boston-based expert on nonprofits, said unions are sometimes run by people who don’t know the rules.

“Unions vary in their sophistication,” said Keating, an assistant professor at Harvard University’s Kennedy School of Government. “Some are small and run like mom-and-pop shops. They may not know how to properly account for and spend funds. Sometimes it is incompetence, but sometimes it’s fraud.”

For their part, State Police officials moved quickly last month to halt some longstanding union practices that had strengthened the labor organization.

On the same day that Pullman resigned, Colonel Kerry Gilpin announced the department would no longer allow the union president and one other union official to receive full trooper’s pay while they worked full time for the union.

Gilpin said the practice conflicted with a state law. But the union, which obtained a court order to stop the change from taking effect, said the provision is contained in the union contract and has been going on, uncontested, for at least 12 years.

The Globe has repeatedly asked Gilpin to comment on the investigation of Pullman, a longtime thorn in her — and her predecessors’ — side. The response? No comment.