On May 12, after a six-week delay caused by the pandemic, the U.S. Supreme Court will hear arguments in the epic battle by congressional committees and New York prosecutors to pry loose eight years of President Donald Trump’s tax returns.

Much about the case is without precedent. Oral arguments will be publicly broadcast on live audio. The nine justices and opposing lawyers will debate the issues remotely, from their offices and homes. And the central question is extraordinary: Is the president of the United States immune from congressional — and even criminal — investigation?

The arguments concern whether Trump’s accounting firm, Mazars USA, must hand over his tax returns and other records to a House committee and the Manhattan district attorney, which have separately subpoenaed them. (There will also be arguments on congressional subpoenas to two of Trump’s banks.)

Trump’s accountants have been crucial enablers in his remarkable rise. And like their marquee client, they have a surprisingly colorful and tangled story of their own. It’s dramatically at odds with the image Trump has presented of his accountants as “one of the most highly respected” big firms, solemnly confirming his numbers after months of careful scrutiny. For starters, it’s only technically true to say Trump’s accounting work is handled by a large firm.

In fact, Trump entrusts his taxes and planning to a tiny, secretive team of CPAs who have operated at various times from humble quarters in Queens and two Long Island office parks. That team, which has had two leaders with back-to-back multidecade terms, has been working for the Trumps since Fred Trump began using the firm back in the 1950s. It was eventually subsumed into Mazars USA, the American arm of a large international firm, through a series of mergers over decades.

One theme has been consistent: partners and sometimes the firm itself have faced accusations of fraud, misconduct, and malpractice on multiple occasions, an investigation by ProPublica and WNYC has found.

This story was co-published with ProPublica; visit their website to read Peter Elkind's full text story on President Trump's relationship with his accounting firm. Stay up to date with email updates about our investigations into the president’s business practices.