A top prosecutor working on the Southern District of New York's criminal investigation into former President Donald Trump revealed that the investigation has been suspended "indefinitely" in a letter announcing his resignation.

Former federal prosecutor Mark Pomerantz, who came out of retirement to work on the Trump investigation, handed in his resignation last month along with a blistering critique of District Attorney Alvin Bragg's decision to stop pursuing an indictment against Trump. In his letter, which was first reported by the New York Times, Pomerantz claimed Trump was "guilty of numerous felony violations" and said it was "a grave failure of justice" not to indict the former president.

Pomerantz and Carey Dunne, another prosecutor, had been leading the investigation into Trump under the direction of former District Attorney Cyrus Vance. They both resigned last month after Bragg had made the decision to pause the investigation.

Trump has repeatedly referred to the investigation as a political "witch hunt" and asserted his innocence.

Most news reports on Pomerantz's letter have focused on his accusation that Trump committed crimes.

“The team that has been investigating Mr. Trump harbors no doubt about whether he committed crimes — he did,” Pomerantz wrote in the Feb. 23 letter.

However, Pomerantz wrote that Bragg "reached the decision not to go forward with the grand jury presentation and not to seek criminal charges at the present time."

"The investigation has been suspended indefinitely," he revealed, which indicates that regardless of what Pomerantz believes, the district attorney does not think that he can prove Trump committed any crimes in a court of law.

"Of course, that is your decision to make," Pomerantz wrote to Bragg. "I do not question your authority to make it, and I accept that you have made it sincerely."

He added that "a decision made in good faith may nevertheless be wrong."

"I believe that your decision not to prosecute Donald Trump now, and on the existing record, is misguided and completely contrary to the public interest," Pomerantz wrote. "I therefore cannot continue in my current position."

According to the New York Times, Pomerantz and Dunne planed to charge Trump with falsifying his annual financial statements, which is a felony in New York. Bragg, who was elected district attorney last year, took over the case after Vance's term expired. But while Vance had moved the district attorney's office toward an indictment of the former president — which would be a historic first — Bragg ultimately reversed that decision, unconvinced there was enough evidence to win the case.

Fox News reported that prosecutors looking for Trump to have illegally inflated his financial statements instead found that he had undervalued his assets.

The details of Trump's "Statement of Financial Condition," which reported "his company's assets, liabilities, and abilities to raise and use funds," included "caveats" which "refuted" claims prosecutors eager to charge Trump with crimes had made, according to Fox News.

"It is a great tribute to the system that Alvin Bragg came in and stopped the unfairness against Trump," an anonymous source close to the investigation told Fox News. "Bragg and his team did the legally and morally correct thing, and they didn’t go the typical political route."

"Bragg said the case is not provable," the source added.

Publicly, the district attorney's office maintains that the probe into Trump's financial activities "continues."

"A team of experienced prosecutors is working every day to follow the facts and the law," a spokesperson for Bragg told Fox News. "There is nothing we can or should say at this juncture about an ongoing investigation."

But the fact remains that the district attorney is not moving towards an indictment of Trump, which serves as a stinging defeat for anti-Trump pundits who for years have salivated at the idea that "the walls are closing in" on the former president.

The only indictments filed as part of Vance's highly publicized probe were tax fraud charges levied against the Trump Organization and its finance chief Allen Weisselberg.

Weisselberg is accused of failing to pay taxes on about $1.7 million worth of fringe benefits, including apartment rent, car payments, and school tuition collected from Trump's company. Legal experts have called these charges "highly unusual,"

Both Weisselberg and the Trump Organization have pleaded not guilty.