NEW YORK — Additional indictments may be forthcoming in the Manhattan district attorney's long-running investigation into former president Donald Trump's company and its finances, an attorney for the Trump Organization's chief financial officer, Allen Weisselberg, said in a court proceeding Monday.

The attorney, Bryan Skarlatos, added that prosecutors recently handed over a trove of new evidence, including tax documents found in the basements of "co-conspirators." It's not clear what co-conspirators he was referencing or how significant the new documents are to the case.

In the hearing, which marked the first court appearance for Weisselberg, 74, since his July arrest in an alleged 15-year tax fraud scheme, a judge tentatively scheduled the trial to begin next summer. The Trump Organization is also indicted as an entity and could face monetary sanctions and other consequences that could cripple or seriously harm the Trump family's business.

Weisselberg’s lawyers were granted a lengthy deadline extension to file their pretrial motions after arguing they are overwhelmed by the pretrial discovery they have already received — 6 million pages of documents. More records from prosecutors are expected to be turned over soon.

Skarlatos said his team would need to examine 25,000 to 30,000 pages a day, seven days a week, to conclude the review within four months.

In arguing for extra time to file, Skarlatos suggested even more evidence may be coming that his team will have to review — possibly because new defendants may soon be in the mix. If others are charged, there may be reason to raise additional arguments that Weisselberg’s legal team could not foresee.

“We have strong reason to believe there could be other indictments coming,” Skarlatos said in court Monday. “Again, we’re shooting at a moving target.”

The district attorney’s office declined to comment after the hearing on Skarlatos’s statement about future potential charges against others. It is unclear who else prosecutors may be considering charges against, but Matthew Calamari Sr., another longtime Trump Organization executive, has been a focus of the prosecution team since the original indictment was filed, people with knowledge of the investigation previously told The Washington Post.

Nicholas Gravante Jr., an attorney for Calamari, said they have had no indication that he might be indicted.

“We remain in discussions with the District Attorney’s Office relating to Matthew Calamari, but continue to believe there is no basis for indicting him,” Gravante said in a statement to The Post. “If they presently intended to indict him, I would have been informed.”

In court on Monday, prosecutors argued that Weisselberg’s team was exaggerating the difficulty of sorting through documents. Assistant District Attorney Solomon Shinerock said the “core documents” in the case were turned over when Weisselberg was arraigned on charges including tax fraud, conspiracy, grand larceny and falsifying business records. Shinerock added that Weisselberg, who has been at the company for 35 years, “is no stranger to these documents.”

At the hearing, New York Supreme Court Justice Juan Merchan gave Skarlatos until Jan. 20 to file written arguments that could determine what evidence is put before a jury at a trial, which Merchan said he expects to take place in late August or early September of 2022.

Weisselberg and the Trump Organization are accused of keeping two sets of books in an effort to monitor and cover up rampant state and federal tax cheating, including through compensation to company executives that was not reported to tax authorities, according to prosecutors from the district attorney’s office and the New York attorney general.

Weisselberg, who is alleged to have avoided paying nearly $1 million in taxes, has pleaded not guilty, and the Trump Organization has denied any wrongdoing.

Prosecutors have said that Trump, who has called the case a politically motivated “witch hunt,” personally signed “many of the illegal compensation checks.” The investigation, which is still underway, spans three years and was held up in part by Trump’s dogged pursuit in the court system to try to block the district attorney from obtaining his personal and business tax returns.

In July 2019, the Supreme Court found that Trump was not protected as president from state court proceedings, clearing the way for the district attorney to enforce a grand jury subpoena seeking the records. It was not until February that the office of Manhattan District Attorney Cyrus R. Vance Jr. received the tax returns and related exhibits, following more legal wrangling by Trump attorneys.

The investigation started as a look into hush-money payments made by Trump’s former lawyer and fixer Michael Cohen to two women who alleged affairs with Trump while he campaigned for the presidency in 2016. Trump has denied having affairs with the women.

Cohen, who has said he made the payments on his boss’s behalf, has cooperated extensively with investigators in the case, guiding them through the inner workings of the Trump Organization and the behaviors of its executives. Three of Trump’s adult children — Ivanka Trump, Donald Trump Jr. and Eric Trump — have been entwined in the business for years.

The investigation expanded to include whether the Trump Organization was manipulating the values of real estate assets to gain tax advantages and favorable loan interest rates. (Trump lawyers have defended similar moves as standard practice in the real estate industry.)

The focus of the probe also turned to company executives’ compensation — from free tuition for children to cars and apartments — which would have reduced tax liability for both the company and the employees.

David A. Fahrenthold contributed to this report.