CNN  — 

Geoffrey Berman, the powerful US attorney for the Southern District of New York who has been thrust into the national spotlight for refusing to leave his post, has a long history at the prosecutors’ office in New York and held a position on President Donald Trump’s transition team before going on to investigate a number of Trump associates.

Berman was an associate counsel in the Office of Independent Counsel during the Iran-Contra investigation, where he prosecuted a former CIA employee for tax fraud, before serving as an assistant US attorney in the Southern District of New York from 1990 to 1994.

During his first run as a US attorney, he handled criminal prosecutions involving tax securities and computer hacking violations, according to the department’s website.

He went on to practice in the private sector before helming the US Attorneys Office for the Southern District of New York. After Attorney General William Barr tried to oust him from that position late Friday, saying Berman was set to leave the office, Berman released a remarkable statement refusing to step down.

“I will step down when a presidentially appointed nominee is confirmed by the Senate,” Berman said. “Until then, our investigations will move forward without delay or interruption.”

Barr then sent a letter Saturday, telling Berman that the President had fired him – though Trump denied having done so shortly after.

Appointment initially met with concern

Berman has been the US attorney for Manhattan since 2018. His initial appointment was met with some public and private concerns among the office’s prosecutors and others about his previous associations with Trump.

He had held a position on Trump’s transition team, and the President had personally interviewed him for the US attorney post, which worried members of the office who prize its reputation for independence, according to people familiar with the matter.

Berman had also been a law partner of Rudy Giuliani – though they never worked on a case together at their former firm, Greenberg Traurig, LLP, according to a person familiar with Berman’s time there, and had little involvement with one another.

But in the time since Berman took office, according to people familiar with the matter, New York federal prosecutors have come to support and trust him, saying they believe he has upheld the office’s independence and pursued politically sensitive cases based solely on their legal merits.

During his tenure, the office has prosecuted Trump’s former personal attorney, Michael Cohen, a case from which Berman himself was recused; investigated whether the Trump Organization violated campaign-finance laws; is investigating top Trump confidante Giuliani and indicted the former New York mayor’s associates Lev Parnas and Igor Fruman.

An unusual position among US attorneys

US attorneys are typically nominated by the President and then are required to be confirmed by the Senate, but Berman, who has led the office since January 2018, is neither.

Berman was initially appointed on an interim basis by then-Attorney General Jeff Sessions for a 120-day term. At the time, some Democrats promised to use procedural efforts to block Berman’s nomination, saying his interview with Trump for the job posed a conflict of interest.

When the end of that term came without the White House putting forth a nominee, the judges of the federal district court in Manhattan voted to appoint Berman to remain in the job. As a result, under federal law, he can serve until the Senate confirms a Trump nominee.

“As Interim U.S. Attorney for this same district, he will lead an incredible team of attorneys and investigators and help provide New Yorkers with safety, security, and peace of mind,” Sessions said at the time Berman took his position. “I am pleased to appoint him to this important role.”

Tension with Trump

Trump has been weighing replacing Berman since at least the middle of 2018, two people familiar with the matter told CNN. And he has made references in private to replacing Berman since at least the summer of 2018, they said – only a few months after Berman assumed the role.

The President has grown progressively more upset with the office since it began its investigation into Cohen, and believed its investigation into Giuliani – which was revealed late last year – was meant to damage him politically, one person said.

In addition, Trump’s former national security adviser John Bolton wrote in his forthcoming book that in 2018, Trump offered to help Turkish President Recep Tayyip Erdogan with a Justice Department investigation into a Turkish bank, Halkbank, with ties to Erdogan that was suspected of violating US Iran sanctions.

In a meeting at the G20 in Buenos Aires, Bolton writes “Trump then told Erdogan he would take care of things, explaining that the Southern District prosecutors were not his people, but were Obama people, a problem that would be fixed when they were replaced by his people.” The Justice Department and Berman did, however, bring a case against the Turkish bank in October 2019.

Berman asserted his office’s independence

There has also been tension between Barr and Berman since Barr became attorney general last year.

Barr has attempted to a micromanage certain cases by asking more questions than his predecessors, according to people familiar with the relationship. Berman has pushed back, those people said.

And when career prosecutors clashed with Justice Department leadership over the handling of politically sensitive cases, Berman asserted his office’s independence.

“The Southern District of New York has a long history of integrity and pursuing cases and declining to pursue cases based only on the facts and the law and the equities, without regard to partisan political concerns,” he said in March.

“My primary commitment is and has been to maintain those core values and that’s how our office is operating.”

CNN’s Erica Orden, Kevin Liptak, Evan Perez, Kara Scannell and Shimon Prokupecz contributed to this report.