Jeffrey E. Thompson has moved to sell his $1.2 million home on a quiet block in Northwest Washington, has solicited buyers for his $355 million-a-year health-care firm, and has sold his interest in the accounting firm he founded and built into a national powerhouse.

It has been a rapid reversal of fortune for the self-made businessman, who quietly wielded his wealth and influence for years before federal agents burst into his home and offices, exposing his role in a wide-ranging criminal investigation into political corruption.

In the months since the March 2 raids, Thompson has withdrawn from his roles as a prominent executive, generous philanthropist and prolific political fundraiser.

The most dramatic gesture came Tuesday, the day federal prosecutors accused Thompson of spending $653,800 on an illicit “shadow campaign” for Mayor Vincent C. Gray (D). In a release that day, the firm known for nearly three decades as Thompson, Cobb, Bazilio and Associates announced that it is now Bazilio Cobb Associates.

A spokeswoman for the firm said chief executive Ralph Bazilio bought Thompson’s stake, listed as 79 percent in a 2007 report by city insurance regulators. The spokeswoman, Barbara Hutto, declined to discuss the terms of the deal.

Thompson had previously stepped down from the firm’s management only weeks after the federal raids. In April, he relinquished his role as chairman of his health-care firm, D.C. Chartered Health Plan, and he is pursuing a sale of that company, which runs the District’s health-care programs for the needy.

District officials have indicated that Chartered’s contract is unlikely to be renewed as long as Thompson remains an owner.

Karen Dale, a spokeswoman for Chartered, said Thursday that sale discussions continue. “We have some offers, and we have a special committee of the board that is designated to review those offers, and we’re in that process at this time,” she said.

Thompson, 57, has not been charged or named in open court or in court filings. But three people familiar with the federal investigation said Thompson is the “co-conspirator” referred to in the prosecution of Jeanne Clarke Harris — a close Thompson associate who has admitted to participating in the shadow campaign and long-running straw donation schemes.

Charging documents in the Harris case describe long-running criminal activity, starting with “straw donation” arrangements that date back to at least 2001. Thompson, according to prosecutors, directed a scheme in which he reimbursed Harris and her companies, friends, relatives and employees for thousands of dollars in donations they made. Authorities allege that Thompson sent $44,000 through Harris to Gray’s 2010 campaign alone.

Prosecutors wrote that Thompson continued his work on the “shadow campaign” at least through New Year’s Eve. That is when he allegedly sent Harris a $161,569 check to cover taxes incurred after he asked her to restate her income on tax returns to reflect the political expenditures.

Ten days later, the Washington Post reported Thursday, Harris met with Gray to discuss the unreported spending.

By that time, Thompson’s once-prodigious campaign fundraising had stopped. In 2011, Thompson played a major role in bankrolling Vincent B. Orange’s successful special-election campaign for an at-large council seat, bundling donations that included $26,000 in money orders that Orange has called questionable. But records show that Thompson has not participated in the 2012 election cycle.

Thompson’s attorney, Brendan V. Sullivan Jr., has declined to comment, citing a policy of not discussing pending investigations. But since April, Thompson’s attorneys have been fighting prosecutors over documents seized from two locations.

The court tussle became public in late May, when a judge unsealed a ruling rejecting Thompson’s effort to prevent prosecutors from reviewing the records, which are said to include more than 60 boxes of paper documents and more than 20 million pages of electronic records.

Thompson’s attorneys have gone to the U.S. Court of Appeals for the D.C. Circuit; oral arguments have been scheduled in the case for Sept. 25. The proceedings remain sealed.

Meanwhile, Thompson has remained in the area, but he has shied away from the social and philanthropic engagements he once graced with his outsize and gregarious presence. He no longer attends galas and parties, where he used to rub shoulders with prominent figures both local and national.

Thompson listed his four-bedroom, three-and-a-half-bathroom colonial last month for $1.175 million. The house, in the Crestwood neighborhood, was placed under contract after less than a week on the market. Thompson bought the house for $366,000 in 1995 from Alexis Herman, the former U.S. labor secretary, who has long been a close friend of his.

Joslyn N. Williams, president of the Metropolitan Washington Council, AFL-CIO, said he used to see Thompson, a fellow Jamaican immigrant, regularly at the gym and at social occasions, including events hosted by Thompson’s favorite charity, the National Council of Negro Women.

He hasn’t seen him since the raid.

“When he’d go home, he’d promise to bring me one of my favorite bottles,” Williams said, referring to Rumona, a Jamaican liqueur. “Jeff, you might say, is a generous individual. Some might say generous to a fault. If he believes in something, he’ll go out of the way for it. . . . When he took on a cause, he really went all out for that cause.”

“We all have our dark side, our Achilles’ heel,” he continued. “We rise to heights, we do good, and then something happens along the way, and we take the wrong path. It’s almost like Greek tragedy. How the mighty have fallen.”