(Bloomberg) -- Manhattan District Attorney Alvin Bragg lashed out at criticism from a former lead prosecutor in his office who investigated Donald Trump, calling it “appalling” and saying his earlier probe of the former president “simply was not ready.”

Bragg made his first comments about Tuesday’s publication of People vs. Donald Trump, a insider’s account of the investigation written by Mark Pomerantz, who was hired by Bragg’s predecessor to look into Trump. 

In the book, Pomerantz criticizes Bragg for deciding not to authorize felony charges against Trump for allegedly misleading financial institutions.

Bragg was asked about the book Tuesday at the end of an unrelated press conference. He said he had thoroughly reviewed the case Pomerantz proposed against Trump and that it was “appalling” that Pomerantz had “insulted the skill and professionalism” of the office’s prosecutors with his criticisms, which began before the book’s publication.

“I did an exhaustive review of a matter put before me and came to the same conclusion that multiple senior prosecutors in my office independently came to,” Bragg said. “And that was that Mark Pomerantz’s case simply was not ready. So I said to my team, ‘Let’s keep working.’ And while Mr. Pomerantz quit a year ago, apparently to write a book, our excellent team continued the work on the case.”

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A spokesman for Pomerantz and a spokeswoman for Simon & Schuster, which published the book, didn’t immediately respond to messages seeking comment on Bragg’s remarks. 

Bragg, who has renewed the probe, said he couldn’t go into specifics on it.

“We have an active, ongoing investigation, so I’m constrained from what I can say,” he told reporters.

Trump has denied wrongdoing and called the investigation, like others into him and his business, a baseless political vendetta. Spokesman Steven Cheung didn’t immediately return an email seeking comment.

Bragg said Pomerantz didn’t provide him with an advance copy of the book to review and hasn’t seen it yet himself. 

“I continue to be concerned that it could jeopardize or undermine our ongoing investigation,” he added.

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