Miami-Dade Mayor Carlos Gimenez, who had voted against the stadium deal as a county commissioner, said "We're going to completely cooperate with whatever the SEC wants. I was against the deal from the get go.''

Gimenez added that he didn't know what the investigation is focusing.

Neither subpoena said exactly what the SEC was looking for, though federal investigations into municipalities generally focus on whether bond holders were misled about finances while being enticed to purchase the bonds.

Two former SEC attorneys who reviewed the subpoenas for The Herald said government investigators are likely looking at whether the city and county did proper due diligence into the Marlins’ finances, and whether there was any influence peddling to local politicians.

“There’s always the issue of pay-to-play. They want to know whether there were unlawful contributions,” said William Nortman, a Fort Lauderdale attorney and former SEC regional administrator. “Don’t forget, there was a lot of controversy over the building of this in Miami. They are examining how this came to be. They want to know whether inappropriate payments were made.”

Due diligence by the county and city into the Marlins’ finances was a key component of auto magnate Norman Braman’s failed court fight two years ago to stop stadium construction. City and county leaders said they never required the Marlins to open their books, though the team often cried poor and argued it needed public funding to stay in South Florida.

But the team’s claim was rebuked in August 2010, when the sports website Deadspin.com revealed that the Marlins were in fact financially healthy, having received more money from baseball’s revenue-sharing system over 2008 and 2009 than anyone in baseball — and pocketing $92 million in revenue-sharing those two years, making a $33 million profit.

Long before the deal to build the Marlins a new ballpark in Little Havana was cemented with a county commission vote in March 2009, the deal was ridiculed as lopsided, with critics complaining that elected leaders kowtowed to a wealthy ballclub owner threatening to leave town. In the end, the Marlins got their way.

The 37,000-seat, retractable-roof stadium ended up being a top-heavy deal for the county, put on the hook for $347 million in construction bonds, a $35 million loan to the Marlins, and $12 million for incidentals such as road repairs. The city’s end of the deal is $94 million worth of parking garages, $13 million toward construction, and $12 million for other improvements.

The county will have to dish out more than $2 billion over 40 years to pay back the principal and interest on the bonds, which were sold under poor market conditions.

The ballclub — which receives virtually all revenues, from concessions to ticket sales for everything from ballgames to soccer matches to concerts — was required only to spend $120 million at the end of construction, on top of repaying the loan to the county in $2 million yearly installments that would serve as rent.

To avoid a tax bill, the county was deeded the footprint of the stadium from the city, and is the property’s owner.

The deal so angered some residents and Braman that it played a part in his successful ouster of County Mayor Alvarez in March.

Braman had fought the three-party deal even earlier, going to court to shut down the construction by calling the agreement a shell game.

Reached Friday amid all the hoopla of Art Basel — the country’s premier art fair, which Braman was instrumental in bringing here — Braman welcomed the SEC investigation, saying: “I feel exhilarated.”

Across town, hammers pounded in nails and cement was poured in anticipation of construction being complete before Opening Day in April.

“Let the truth come out,” Braman said. “Now we’ll know what this whole thing was about and who was really for this travesty.”

Miami Herald staff writer Michael Sallah contributed to this report.