The sprawling civil fraud trial of Donald J. Trump dragged to an end on Wednesday as defense lawyers interrupted a witness who was testifying about the principles of accounting with a spirited argument over the difference between the words “could” and “would.”
The witness, Eric Lewis, a professor at Cornell University’s business school, was the last to appear at the trial, which stems from a lawsuit filed by the New York attorney general, Letitia James, accusing the former president of fraudulently inflating his net worth to obtain favorable treatment from banks and insurers.
The conclusion of Mr. Lewis’s appearance shortly after noon signified the end of the trial’s testimony, though a verdict remains weeks away.
Next month, the parties are expected to submit closing briefs, drawing on evidence to present their cases and argue before the judge on Jan. 11. The judge, Arthur F. Engoron, will then decide the outcome, a decision expected in late January at the earliest.
Ms. James, a Democrat, has asked that Justice Engoron fine Mr. Trump $250 million or more and bar him and the other defendants in the case from running a business in New York. Mr. Trump, a Republican, has said the case is part of a political vendetta against him.
Mr. Lewis’s testimony provided a fitting conclusion to a trial that was occasionally scintillating, but more often stultifying. The proceedings were dry, muddled and characterized by fighting between the parties — particularly when Mr. Trump was in attendance.
The stakes were transformed before the trial even began. In late September, Justice Engoron found in a pretrial ruling that annual financial statements compiled by the former president and the other defendants had contained fraud. The trial became a test of which punishments Mr. Trump would receive, and whether he had violated other state laws.
“While the judge already ruled in our favor and found that Donald Trump engaged in years of significant fraud and unjustly enriched himself and his family,” Ms. James said in a statement, “this trial revealed the full extent of that fraud — and the defendants’ inability to disprove it.”
A lawyer for Mr. Trump did not immediately respond to a request for comment on the conclusion of the testimony.
Ms. James’s lawyers kicked off their case at the beginning of October. For more than a month, lawyers for the attorney general called on witnesses, including experts on the fine points of real estate accounting and three of Mr. Trump’s adult children. Two of them — Eric Trump and Donald Trump Jr. — are also defendants.
The attorney general’s presentation reached its climax with the appearance of Mr. Trump himself, who testified last month. He was unruly, attacking Ms. James and Justice Engoron from the stand. He admitted to making some contributions to the fraudulent financial statements, but he pointed out disclaimers that he has said warned lenders to do their own homework.
The defense’s case began a week later, with Donald Trump Jr. returning to the stand to tout his father’s genius and the resplendence of the Trump business empire. Eric Trump and the former president were also expected to return to testify for the defense, but they both canceled.
Instead, the unlikely stars for the defense were current and former employees from Deutsche Bank, which authorized hundreds of millions of dollars in loans to Mr. Trump. While Ms. James had argued that the former president used his financial statements to persuade the banks to offer more generous terms, the bankers testified that they did not rely on his embellished claims of wealth, and performed their own analysis.
Those standout witnesses were diamonds in the rough. Over more than 40 days, the court heard testimony from more than 40 people, who were interrupted frequently by objections and bitter sniping between the lawyers. Mr. Trump’s lawyers repeatedly accused the judge of bias, made unsuccessful motions for a mid-trial verdict and appealed numerous issues to a higher court that is expected to review aspects of the trial after Justice Engoron rules.
Mr. Trump’s lawyers also made a point, as did the former president, of attacking the judge’s chief law clerk, who sat beside him on the bench and with whom he frequently confided during the proceedings.
After Mr. Trump attacked the clerk, Allison Greenfield, on social media as a Democratic partisan, Justice Engoron issued a gag order barring him from commenting on court employees. Mr. Trump violated the order twice, incurring $15,000 in fines. His lawyers fought it and continually accused Ms. Greenfield of bias until the judge placed a similar order on them.
Mr. Trump had been expected to return to testify this week, but abruptly canceled his appearance on Sunday. When the trial resumed on Tuesday, it was clear that the lawyers fighting on behalf of the former president and the State of New York were exhausted. The attorney general’s team seemed particularly eager for things to wrap up. When Mr. Trump’s lawyers said that a Trump Organization witness might return, they objected in the strongest terms.
“We want the case to end,” said one state lawyer, Kevin Wallace.
But the trial’s last day was marked with frequent interruptions as Mr. Trump’s lawyers objected more than 13 times during an hour of Mr. Lewis’s testimony. He was then cross-examined — and briefly excused so that the lawyers could argue over the relative importance of “could” and “would.”
When the proceeding ended, both parties thanked the court employees for their time.
At least one participant appeared to feel a pre-emptive nostalgia.
“In a strange way, I’m going to miss this trial,” Justice Engoron said. “It’s been an experience.”