Tallahassee Mayor Andrew Gillum’s surprise victory in the race to become the Democratic nominee for governor of Florida was fueled in part by a compelling personal biography: The son of a school bus driver and construction worker, he was the first of his parents’ seven children to graduate from high school and go to college. At age 23, he became the youngest city commissioner the Florida capital had ever seen.

“Between my mother and father, they are the best examples of hard work that I know to this day,” Gillum said Tuesday night, after support from progressives vaulted him over older and better funded primary opponents.

A less savory narrative threatens to collide with that heartening origin tale. Over the past year, a federal grand jury has been conducting a public corruption investigation in Tallahassee. The probe drew little notice beyond the capital during the primary campaign but is attracting new attention with Gillum’s bid to become the first African American governor of the nation’s largest swing state and Florida’s first Democratic governor in 20 years. 

Steven Andrews, an attorney representing former city manager Rick Fernandez, said his client testified before the grand jury in July and was not asked about the mayor. 

Nonetheless, he said, “This has been a cloud hanging over the city, and unfortunately for Gillum and the state of Florida, now it’s going to hurt him. It’s all just too bad because Gillum has got such a great story.”

Over the past year, details have emerged in the local press about Gillum’s relationship with lobbyists and the broader probe — in one report, a city commissioner was photographed frolicking in Las Vegas with undercover agents and a dwarf entertainer. Those reports are expected to infuse a multimillion-dollar spree of attack ads as the GOP battles to keep a decades-old grip on the governor’s mansion.

The precise contours of the probe are unknown, but investigators have subpoenaed information about lobbyist Adam Corey, a longtime friend of Gillum’s who once served as his campaign treasurer. Three people who claimed to be out-of-town developers or business executives who cozied up to public officials for more than a year — before suddenly vanishing — are now widely presumed to have been undercover FBI agents. Last year, two of the purported developers met up with Gillum and Corey in New York. Gillum has acknowledged that the trip is the subject of an investigation by the state ethics commission, as is one Gillum took to Costa Rica with Corey and other lobbyists.

No one has been charged in the federal investigation, and the FBI declined to comment.

The scope of the probe is hinted at by several rounds of grand jury subpoenas that sought correspondence from the city and its Community Redevelopment Agency between several people and their lobbying and real estate firms.

Three of the subpoenas sought documents about Corey and the Edison, a restaurant he and partners built with taxpayer dollars.

A spokesman for Gillum said FBI agents assured the mayor in June of 2017 that he was not a “focus” of the probe.

“I acted in every way in compliance with the law,” Gillum said. “I acted in every way consistent with the law.”

Chris Kise, Corey’s attorney, said his client is not a target and has done nothing wrong. He declined to answer specific questions about the investigation.

Gillum’s opponent, Rep. Ron DeSantis for Florida’s 6th congressional district, wasted no time after winning the Republican nomination Tuesday before drawing attention to the ethics complaint against the mayor and seeking to link him to the FBI probe.

“He is embroiled in a lot of corruption scandals,” DeSantis said on Fox News. “This guy can’t even run the city of Tallahassee. There is no way Florida voters can entrust him with our entire state.”

Gillum has called the trips to New York and Costa Rica personal, saying he paid his own way and discussed no city business. But at times he has resisted answering questions about the trips, and has not yet made good on a pledge to release receipts of his payments. Gillum spent the past year refusing, for example, to say whether he saw the Broadway hit musical “Hamilton” with his lobbyist friend while he was in Manhattan. (He did, he told The Washington Post on Thursday.)

“It’s easy to see these things in the light of aftermath: ‘Oh, lobbyist.’ What about friend, somebody I’ve known before he was ever a lobbyist?” Gillum said. “In the aftermath you look back on these things and you go, now that you get to review them in the light that you do, if you’re just a person that doesn’t know the relationship, ‘Well, why is the mayor hanging out with a lobbyist?’ It isn’t like that.”

Though it was not publicly known at the time, the federal probe began in 2015, when undercover agents swept into town posing as “real estate developers and medical marijuana entrepreneurs to gain access to various city officials,” according to an FBI search warrant.

Soon, they were pitching development proposals — and socializing. A “developer” who went by the name Mike Miller started exercising in the mornings at a gym with Corey and Gillum, Gillum said.  

In May 2016, Gillum and his wife vacationed with Corey and other lobbyists and their significant others at a villa in Costa Rica that has oceanfront views and rents for $1,400-per-night, according to a web listing. The mayor has said he paid his share of the villa in cash.

While they were in Costa Rica, Corey sent Gillum an electronic invitation for tapas and drinks later that month at the Edison with “Miller” and a Miller associate who went by the name Brian Butler, according to an email released in response to a public records request.

Corey and his business partners had used $2.1 million in tax dollars to build the Edison, converting a 1920s-era electric plant owned by the city into a swanky restaurant of exposed brick overlooking a park studded with palm trees. In 2013, as a city commissioner, Gillum voted in favor of funding the project. City legal officials determined he did not have a conflict of interest, records show.

Geoff Burgan, a spokesman for Gillum, said the mayor recalls the meeting at the Edison as “remarkably unremarkable,” the kind an elected official often takes with people interested in doing business in the city. The men said they were interested in building on the south side of Tallahassee, but did not have concrete plans, Burgan said.

Three months later came the gathering in New York. Gillum was headed there for his former job with the People for the American Way Foundation, the charitable arm of a liberal advocacy group. Corey wanted to meet up, Gillum said. According to a Google calendar invitation obtained by the Tallahassee Democrat, “Miller” arranged rooms at the Millennial Hilton and outings to a Mets game and a boat trip.

In June of 2017, the subpoenas started to arrive at city hall. They did not name the mayor.

Around the same time, the public got what many believed was an unusual window into the investigation. 

Josh Doyle, an FBI agent, had applied to work as executive director of the Florida Bar. In his job application, Doyle described building a team of 20 people that included “undercover employees, forensic accountants, intelligence analysts, auditors and support staff.”

“I recently concluded a sensitive two-year undercover investigation,” Doyle wrote. The job application was publicized by the Tallahassee Democrat, along with a video of his job interview. His comments led many in the city to believe indictments were imminent.

Doyle declined to comment.

Gillum started fielding questions about the New York trip in August 2017, when local television station WCTV published a photo showing Corey, Gillum and “Miller” — his face blurred out at the request of the FBI — on a boat with the Statue of Liberty in the background. Gillum told the television station that the excursion was entirely personal, with no city money expended nor city business discussed.

Then reporters began asking about his rumored attendance at a performance of “Hamilton.”

On Thursday, he told The Post he didn’t ask questions when his brother Marcus Gillum handed him a ticket.

“I’m sketchy on the details, all I know is I got handed my ticket from Marcus. We’re going to ‘Hamilton,’ ” Gillum said. “I thoroughly enjoyed it. I had a great time.”

They sat in what Gillum described as one of the upper levels of the Richard Rodgers Theatre, where tickets can go for hundreds of dollars. Gillum said he didn’t ask how much the ticket cost or who paid for it. He said he assumed his brother paid for it; the two of them often buy concert tickets for one another, he said.

“I would never ask, ‘How much did this cost?’ ” Gillum said.

Florida law prohibits elected officials from accepting any gift worth more than $100 from a lobbyist or vendor doing business with the city. Those rules, however, do not bar gifts from family members and do not require that such gifts be reported.

Gillum said he learned only later that the ticket he used had been given to his brother by Corey, in exchange for a ticket to a Jay-Z show. That detail surfaced, Gillum said, when a lawyer he hired for the state ethics inquiry interviewed his brother Marcus. Gillum has not reimbursed anyone for the ticket, Burgan said, and neither Burgan nor the mayor said they knew the price of the tickets to either show. 

In a brief interview Thursday evening, Marcus Gillum declined to answer questions about the New York trip. 

In February of 2018, in another unexpected window into the investigation, the Tallahassee Democrat reported the contents of a search warrant application that had been filed under seal but inadvertently made public. An FBI agent wrote in an affidavit that city commissioner Scott Maddox directed a ride-sharing company to hire his former lobbying firm, Governance Inc., and then voted to pass an ordinance that benefited the company. Maddox received tens of thousands of dollars from Governance during that time, the agent wrote, and hundreds of thousands since 2012. 

Maddox has served as Tallahassee mayor and Florida Democratic Party chairman and launched three unsuccessful campaigns for statewide public offices.

Maddox’s attorney, Stephen Dobson, said: “Misleading or incorrect information has been improperly leaked alleging misconduct that never occurred. Scott Maddox has served his community with distinction and honor and is known as an honest public servant.”

In a June interview with The Post’s Jonathan Capehart, Gillum discussed the investigation and the affidavit. “It is clear this investigation has zeroed in on a colleague of mine, which I deeply regret, and maybe some other individuals,” he said. 

He also said he had parted ways with Corey, his friend of 20 years.

“We’re all entitled to be disappointed by our friends when they disappoint us,” Gillum said. “No one should draw the conclusion, and I certainly don’t believe there’s any evidence to suggest this, that I’ve done anything inappropriate at all as it relates to my vote and how I conduct myself on the city council.”

Kise, Corey’s lawyer, accused the mayor of “throwing Adam under the bus.”

“The best thing that has happened to Andrew Gillum is he’s now the Democratic nominee for governor of a major state,” Kise said. “But maybe the worst thing that has happened to him, in terms of the ongoing investigation, is that he is now the nominee.

“When he was an also-ran, nobody really pressed on the hard questions,” he added. “Now, as is ultimately true for all of us, there comes a day of reckoning, and he is going to come under far more scrutiny.”

Ellen Nakashima contributed to this report.