The People of the State of New York v. Donald J. Trump, et al, is scheduled to get underway in lower Manhattan at 10 a.m. with opening statements.

If opening statements are completed before the end of the day, the New York attorney general plans to begin her case by calling Trump's former Mazars USA accountant Donald Bender to the stand.

Mazars severed its business relationship with the former president last year after learning of the attorney general's findings during the AG's probe.

Though Trump has denied all wrongdoing alleged by the attorney general, Judge Arthur Engoron has already decided the central allegation against Trump and his co-defendants, ruling in a pretrial hearing last week that the AG had provided "conclusive evidence" that Trump overvalued his assets between $812 million and $2.2 billion.

The judge then canceled the Trump Organization's business certificates in New York, severely restricting Trump's ability to conduct business in the state moving forward -- a move that Trump attorney Alina Habba called "nonsensical" and "outrageously overreaching."

"In defendants' world: rent regulated apartments are worth the same as unregulated apartments; restricted land is worth the same as unrestricted land; restrictions can evaporate into thin air," Engoron wrote, citing multiple arguments made by defense to justify the allegedly inflated valuations of Trump's assets. "That is a fantasy world, not the real world."

Among the issues still to be determined at trial: What additional penalties Trump might face, and what might happen with the multiple causes of action included in the attorney general's suit.

Former President Donald Trump stepped up his attacks on the judge overseeing and deciding his case, writing on Truth Social overnight that Justice Arthur Engoron should resign and be sanctioned for "abuse of power."

Similar to an earlier post, Trump criticized allegations regarding the value of his Mar-a-Lago estate, in addition to an appellate court's ruling that his lawyers unsuccessfully tried to use to limit the timeframe of the case.

Former President Trump posted on his Truth Social platform Sunday night that he intends to attend the opening of the trial.

"See you in court -- Monday morning," he wrote in a post.

Earlier Sunday, multiple sources familiar with the decision told ABC News that Trump was expecting to attend.

Trump will have no speaking role in court on Monday, but it is anticipated that he'll return to the courthouse toward the end of the state's case when court records show he will be called as a witness.

Doug Larson's name appears across five years of Donald Trump's financial documents, according to records entered into evidence.

A longtime professional appraiser with the real estate firm Cushman & Wakefield, Larson was cited in Trump Organization documents as an expert at valuing properties like 40 Wall Street, Trump Tower, and an adjoining retail space called "Niketown." Spreadsheets entered as evidence explicitly reference multiple phone calls with Larson between 2013 and 2017.

When asked about these phone calls in court, Larson testified that no such conversations occurred.

"Is it fair to say that Mr. Trump valued Trump Tower at $526 million in conjunction with you?" state attorney Mark Ladov asked Larson.

"No, that is incorrect," Larson said.

"Were you aware that Mr. McConney was citing you as a valuation source in his work papers?" Ladov asked.

"No, I was not," replied Larson, who said he did not assist Trump Organization executives in valuing Trump Tower, Niketown, or 40 Wall Street, despite Trump's paperwork referencing him as a source.

Evidence presented by the state instead suggested that the valuations were determined using cherry-picked metrics from a generic email Larson sent clients.

"It's a way to get your name out to clients for potential work," Larson said about one such "email blast" that was used in a Trump Tower valuation.

Larson added that the valuations Trump Organization executives determined based on "consultation" with him used flawed methodologies, such as using capitalization rates related to office buildings to appraise the retail Niketown building.

"It doesn't make sense," Larson said about Niketown's $287 million valuation.

"It's inappropriate and inaccurate," Larson said about the Trump Organization relying on his name to support their valuations. "I should have been told, and appraisals should have been ordered."