Gov. Ned Lamont’s former budget deputy fought back at his bribery and extortion trial on Tuesday.

In a heated exchange, Kosta Diamantis’ attorney accused a star witness of being an opportunistic liar – and suggested that the governor’s office tacitly approved of Diamantis’ actions.

But is it enough to counter hundreds of incriminating e-mails, texts, and voice messages?

Diamantis’ lawyer came out swinging against John Duffy, a masonry contractor who said his company paid Diamantis nearly $100,000 in bribes in exchange for multimillion-dollar school construction contracts.

“How is this jury able to tell when you’re lying and when you’re telling the truth?” defense attorney Norm Pattis asked. “You’re nervous and you’re in trouble now, aren't you?"

Duffy spent a day-and-a-half on the witness stand, going over texts between him, his boss and Diamantis.

Among them was an e-mail from Diamantis saying, “Doesn’t matter end of day you gone [sic] add 70." Duffy testified that was a $70,000 bribe for a school construction job in Tolland.

Other texts referred to bringing Diamantis a “birthday card” at a January 2020 dinner – even though Diamantis’ birthday is in June.

“It’s like a code word I use for payments,” Duffy told jurors. “Because I wanted to be discreet.”

But Pattis, a well-known and sometimes controversial defense attorney, suggested that Duffy was actually using Diamantis and concealing payments to him.

“You were shaking him down,” Pattis said. “You wanted a cut.”

The witness shot back: “There’s no way your client was getting $17,000 and giving me 10. That’s ridiculous.”

Duffy admitted that he lied to federal investigators on several occasions.

“I was afraid and I was trying to cover up for myself and Kosta and [company owner] Sal Monarca,” he told jurors. “The testimony I gave to this court is the truth.”

The cross-examination got so tense that Judge Stefan Underhill warned: “Hold on, we’re not going to let this get argumentative."

After Duffy’s testimony, another contractor took the stand with more explosive allegations.

Antonietta Roy, who owns Construction Advocacy Professionals (CAP), a project management company, said she paid Diamantis $1,000 in cash out of her window on the side of the road.

"I felt like a drug dealer," she told jurors.

Roy said Diamantis pressured her to "take care of" his daughter by creating a $45 an hour job for her – plus bonuses.

“I hired her because it was Mr. Diamantis’ daughter,” Roy told jurors. “I gave Mr. Diamantis money because I was afraid I wouldn’t get future work.”

Roy said Anastasia Diamantis worked few hours and did little work.

“She didn't do what she was asked. She did not attend any meetings,” Roy said. “I couldn’t let her go. It was Mr. Diamantis’ daughter … because I needed to keep him happy.”

Roy also testified that Diamantis rigged a bid in her favor, telling her CAP needed to lower its bid on a project at Bulkeley High School in Hartford. The company ultimately won the $1.7 million contract – even though another bidder contested the decision and the school district already had its own project administrator.

“Mr. Diamantis had told me had created the construction administrator position on that project for us to be on it,” Roy told jurors.

Prosecutors showed jurors several checks Roy wrote to Diamantis. She testified the defendant called them "political donations" – but "the calls were constant for money."

Roy, Duffy and Monarca already pleaded guilty to conspiracy to bribe Diamantis.

Diamantis was a top budget deputy to Lamont. 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.

On Tuesday, Pattis suggested that the governor’s office placed pressure on Diamantis to “get these projects done on time and under budget."

He may call the governor as a witness.

“I have no idea [why],” Lamont said on Wednesday. “As soon as we got some wind that something may not be right, we changed the actors there. But I’ve got to do everything I can to make sure something like this can never happen again.”

Outside the courthouse, Diamantis told reporters that he is eager to tell his side of the story.

“When the time comes, I will provide you with a statement. You will probably hear my testimony – when the time comes,” he said. “You will get a response from me when the time is appropriate for the court, myself and the people. Not now; not because you’re asking for it.”