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.

Testifying for the defense, former President Trump's eldest son described his father as a real estate "visionary" who "sees the sexiness in a real estate project," creating value for the family business that cannot be captured on paper.

Donald Trump Jr. began his testimony with a quip after Judge Engoron welcomed him back to the stand following his testimony earlier in the month.

"I'd say it's good to be here, but the attorney general would probably sue me for perjury," Trump Jr. joked.

In his testimony, Trump Jr. described the Trump Organization as "a large family business," with Trump and his eldest children at the top and other executives handling many of the details.

"If there were numbers and things, I would rely on them to give me that," Trump Jr. said.

He recounted the history of the Trump Organization, beginning with his great-grandfather who he said built hotels in the Yukon Territories of Canada. His grandfather, Fred Trump, "started working on job sites around Queens, learned the trades" and eventually "created an incredible portfolio, by the time of his passing, of rental apartments in Brooklyn and Queens."

A state attorney jokingly objected that references to the 1800s were outside the statute of limitations -- then more seriously objected to the history lesson's relevance.

"I think it is relevant to get the historical perspective -- I find it interesting," Judge Engoron said in overruling the objection. "Let him go ahead and say how great the Trump Organization is."

Trump Jr. obliged.

"My father learned a lot of the business from him, but had some flair and saw New York City and Manhattan as the ultimate frontier," he said. Speaking of Trump Tower, he said, "I think it would have been one of the first, I think great, ultra-luxury real estate emerging in Manhattan."