A cash bribe in a restaurant bathroom just blocks from the state Capitol, “endless demands for money” and lies to FBI investigators.

That’s what a former top state budget official was accused of during the first day of his corruption trial in Bridgeport Federal Court.

The case could expose the inner workings on Gov. Ned Lamont’s administration – and the governor himself may even be called to testify.

If you wanted to build a school, you had to go through Kosta Diamantis. As head of the state’s Office of School Construction Grants and Review (OSCGR) from 2018 to 2021, he oversaw hundreds of millions of dollars in school building grants.

But on Monday, Diamantis went on trial, accused of shaking down contractors for money and favors – in exchange for multimillion-dollar construction contracts in Hartford, Tolland and New Britain.

“The defendant used that power, that authority, that influence, to demand bribes from contractors,” Assistant U.S. Attorney Jonathan Francis told jurors. “He begged and pleaded and eventually threatened to hurt Acronom’s business.”

Acronom is one of two companies that Diamantis is accused of accepting money from. The masonry company’s former vice president, John Duffy, testified they Diamantis tens of thousands of dollars to secure a $3 million construction contract at Weaver High School in Hartford.

“Without Kosta’s involvement or influence, we probably wouldn’t have got that job,” Duffy told jurors.

Prosecutors also accuse Diamantis of threatening to “blackball” another company, Construction Advocacy Professionals (CAP), if they didn’t create a job for his daughter.

CAP’s former president, Antonietta DiBenedetto Roy, has already pleaded guilty to conspiracy to bribe Diamantis, along with Duffy and Acranom’s owner, Sal Monarca.

Diamantis had little to say as headed into the first day of his trial.

"When the time comes, I will testify,” he told reporters.

But jurors heard plenty from Diamantis, through dozens of text messages and voice mails between him, Duffy and Monarca.

In one text message from 2019, Diamantis allegedly tells them both: “I am very good at what I do … And I always usually work at 5% of total just FYI.”

As time went on, the texts become more frequent and urgent, with Monarca calling Diamantis a “vulture.”

“I shouldn't have to beg,” one alleged text from Diamantis reads. “I need 5k [sic] desperately tomorrow from him or anyone. I don’t care who. I shouldn’t have to beg - he owes me 77 [thousand dollars] two months ago.”

In a voice mail, Diamantis allegedly pressured Acranom to pay him: “Even though [Monarca] hasn’t kept his part of the bargain, I have to keep mine … I didn't ask for the maximum. I asked for the minimum of what we bid.”

Although the first day offered plenty of drama, Diamantis’ defense may be the most revealing part of the trial.

He may call Lamont to testify, although the governor insists that he was unaware of any wrongdoing until federal investigators got involved in 2021.

“I didn’t hire him. I fired him as soon as I found out there was something untoward going on,” he said on Friday. “Kosta’s attorney is subpoenaing everybody, and I'm told they’ve asked for me as well.”

Diamantis’ attorney is Norm Pattis, who also represented conspiracy theorist Alex Jones in a $1.4 billion defamation lawsuit brought by the families of Sandy Hook shooting victims.

On Monday, Pattis said his strategy is to “create doubt.”

A year before the FBI investigation, in 2020, a Stamford demolition company warned the Lamont administration of “an effort to circumvent the lawful public bidding requirements.”

Lamont’s former budget secretary, Melissa McCaw, resigned amid the scandal. She moved OSCGR to the governor’s budget office from the Department of Administrative Services, where grans received more scrutiny.

It’s not clear if Lamont will agree to testify, but Pattis said he believes the governor has something to add.

“I do think he has something to add,” Pattis said. “I’ve discussed it with the governor and with the attorney general's office last week. And we'll save the evidence for the courtroom.”

Prosecutors also plan to call school officials who claim Diamantis pressured them to use certain contractors, even when they objected. Jurors will also see videotaped FBI interviews where Diamantis allegedly lied to investigators.

Diamantis’ trial could last almost a month, but his legal troubles will not be over then.

In January, he goes on trial again – accused of taking bribes to kill a Medicaid audit.