ST. PETERSBURG — Federal agents on Thursday raided the headquarters of Universal Health Care, the once high-flying Medicare insurer plagued in recent months by allegations of fraud and embezzlement.

"They started yelling, 'Everybody away from your computer. We have a search warrant,' " said Michelle Yancey, one of hundreds of employees ordered to leave Universal's downtown headquarters shortly after 8 a.m.

The raid by FBI agents comes the same week that a bankruptcy court trustee alleged a "pattern of dishonesty or gross mismanagement'' at Universal including "side deals'' that benefited insiders.

Among the examples cited: a transfer of more than $18.3 million to another company controlled by Universal founder Dr. Akshay Desai last year and $2.2 million in "bonuses and "other compensation'' to company officers and directors in addition to their salaries, also in 2012.

The FBI would not comment about the investigation Thursday. Investors, some of whom put their life savings in Universal, said the agents would likely focus on Desai, Universal's former CEO and until recently a member of the state Board of Education and finance chairman of Florida's Republican Party.

"He is going to pay for his mistakes because something is not right,'' Dr. Rajendra Gupta, a Fort Lauderdale physician who invested $4 million, said Thursday. "He told me he can do whatever he wants and does not have to listen to me or any other investor.''

Florida insurance regulators were already in the process of liquidating Universal by April 1. The parent company filed for bankruptcy last month.

The collapse leaves more than 800 employees without jobs, scores of providers unpaid and thousands of members searching for alternative plans to cover their health care needs.

Even as Universal struggled financially, Desai drew a $900,000 salary and another $2.5 million or more in bonuses and other compensation last year, according to a trustee overseeing Universal's bankruptcy case.

Desai, 55, could not be reached for comment. No one answered the door at his $2.6 million bayfront Snell Isle mansion Thursday morning. In the evening, a burgundy SUV and a dark silver Audi R8 sports car sat in the driveway, but the gates to the property were closed.

Until a few weeks ago, Desai was a much-courted figure in state and national Republican circles because of his prominence in the Asian-American community and political contributions totaling nearly $650,000. He visited President George W. Bush at his ranch in Texas, talked up Rick Perry until the Texas governor dropped out of the 2012 presidential race, then turned his support to GOP nominee Mitt Romney.

Desai was especially close to former Gov. Charlie Crist. In an opinion piece in the Tampa Bay Times last fall, Desai wrote that he personally contributed or raised about $2 million for Crist's campaigns since 1992.

The two men, though, had a falling out last summer when Crist, now a Democrat, endorsed President Barack Obama.

An Indian-born gerontologist, Desai saw his star rising even before he founded Universal Health Care in 2005 and quickly built it into Florida's fourth largest Medicare health management organization. Such HMOs use federal Medicare funds and members' enrollment fees to provide more services than covered by regular Medicare.

Starting in 2006, Universal's Any, Any Any plan — members purportedly could see any doctor anywhere at any time — drew thousands of members but also complaints of false advertising, poor customer service and denied medical treatments. The company temporarily suspended enrollment, and in 2008 signed an agreement with state regulators to beef up reserves to handle the swelling volume of claims.

Over the next few years Universal continued to grow, eventually expanding to 23 states and serving 140,000 members. In 2010, it spent $9 million for a new headquarters on Central Avenue in St. Petersburg and another $750,000 for renovations.

It paid more than $500,000 for a 28th floor condo in nearby Signature Place, known for its sleek architecture and sweeping views of the waterfront. Employees joked that Universal needed the condo as temporary housing for the many executives who cycled through — the company had five chief financial officers in six years.

The company also contributed $81,000 to Republican candidates and causes, on top of Desai's personal donations.

"He was giving money to the Republican Party without consulting any of the investors or anyone else in the company,'' said Gupta, the Fort Lauderdale doctor.

For the past three years, Medicare officials hammered Universal for poor quality, urging potential members to use caution before selecting it.

The first public notice that Universal was in serious financial trouble came in November when it agreed to stop selling Medicare policies in Georgia. That state's insurance commissioner cited Universal's net loss of $22.1 million in the first six months of the year as reason for the halt.

On Feb. 4, the Florida Office of Insurance Regulation deemed Universal nearly insolvent and accused executives of a broad pattern of financial mismanagement — including fraud and diversion of funds — under Desai's leadership.

Two days later, Universal Health Care Group filed for bankruptcy, listing $50 million to $100 million in assets and $10 million to $50 million in liabilities. Among those to whom the company said it owes an "undetermined'' amount: Desai and his wife, Seema.

As FBI agents poured into Universal's headquarters Thursday morning, employees realized that the end of the company meant an end, also, to their paychecks and health insurance.

"One colleague of mine is pregnant, almost about to give birth,'' said employee Bryan Frankel.

Charleen Reynolds, an auditor for Universal, said she had just set her bag down when three FBI agents told her to leave. Many of her colleagues didn't have time to grab their resumes off their desks for a job fair planned for later in the morning.

"Everything that has been said has been to pacify us," she said. "A lot of false hopes and false promises.''

Other employees wondered why Universal had not given employees 60 days' notice as generally required in cases of mass layoffs.

Also left in limbo are thousands of Universal members who must find new Medicare plans. The hitch is that any change in coverage won't take effect until the first day of the month after the request is received. So if enrollees wait until next week to pick a new private plan, they will have to wait until May 1 for it to become effective — and face higher out-of-pocket costs in the meantime.

The biggest dollar losses will be to Universal's investors, including many of Desai's fellow Asian-American doctors who answered his call for capital in the company's early days. Dr. Zachariah P. Zachariah, chairman of the Florida Board of Medicine, invested more than $6 million. He was kicked off Universal's board in 2009, as Desai moved to gain total control of the company, Zachariah alleged in a pending lawsuit.

"He called me about a week ago, '' Zachariah said Thursday, "but I didn't want to talk to him. There is nothing to talk about.''

Times news researcher Connie Humburg contributed to this report. Susan Taylor Martin can be reached at susan@tampabay.com. Jeff Harrington can be reached at jharrington@tampabay.com and (727) 893-8242. Meredith Rutland can be reached at mrutland@tampabay.com.