• An ex-prosecutor in Manhattan DA's office compared Donald Trump to mafia boss John Gotti.
• "He demanded absolute loyalty," Mark Pomerantz said of Trump in his new book, per NYT.
• Pomerantz served in the DA office from early 2021 until his resignation a year later.

A prominent ex-prosecutor accused former President Donald Trump of building his business empire "through a pattern of criminal activity" and compared him to the late mafia boss, John Gotti, according to a New York Times report on Friday.

Mark Pomerantz, a former prosecutor in the Manhattan district attorney's office, made the comments in his forthcoming book, "People vs. Donald Trump," of which The Times obtained an advance copy.

"He demanded absolute loyalty and would go after anyone who crossed him. He seemed always to stay one step ahead of the law," Pomerantz wrote of Trump, according to The Times. "In my career as a lawyer, I had encountered only one other person who touched all of these bases: John Gotti, the head of the Gambino organized crime family."

A lawyer for Trump in a recent letter threatened legal action against Pomerantz for "defamatory statements against my clients" and said on Friday that "injecting the name John Gotti into this seems like just another desperate attempt by Pomerantz to sell books," per The Times.

A spokesperson for Trump did not immediately return Insider's request for comment.

Pomerantz had helped lead the investigation into Trump and his businesses in the Manhattan DA's office from early 2021 until his resignation a year later. He left after the new Manhattan DA, Alvin Bragg, refused to pursue charges against the former president.