The Times reports:

Now, as federal and local prosecutors examine the web of deceitMr. Santos spun on his way to winning a closely contested House seat last November, they appear to be focused on a trail of financial dealings that suggests possible campaign finance violations or outright fraud. Campaign filings listed donations that exceeded the legal limit, hundreds of thousands of dollars in unexplained spending and a strange string of expenses for $199.99 — just pennies below the threshold beyond which receipts are required.

"There are very fundamental errors that no accountant of her experience would make," said Brett G. Kappel, a bipartisan elections lawyer. "If she submitted these knowing they contained false information, there are going to be consequences."

Likewise, the Timesreports:

But while the kind of egregious irregularities in Mr. Santos's reports do not appear in other campaigns she worked on, The Times found that Ms. Marks's accounting and business practices repeatedly drew suspicion. Former clients have taken her to court, saying she overpaid herself or failed to pay bills, as have a long line of creditors. Her close business ties with a felon alienated some onetime allies.

Former Long Island GOP congressional candidate Peter Zinno sought assistance from Marks in 2010, and according to the Times, she told him she'd "charge him half of her usual rate because, 'She liked me, apparently,' Zinno said.

However, the former Republican candidate eventually discovered, "Nancy is a hustler, and I got taken," he said.

Zinno later found "during his campaign, Ms. Marks had doubled the monthly rate paid to her company without notice," and even "appeared to bill him twice" some months, which led him to sue in 2013 for $3,800.

The judge did not grant him the requested settlement due to "lack of sufficient evidence," theTimes reports — "in part because he had waited too long to lodge his claim."

According to theTimes, it will be on investigators to decide whether the former Santos staffer "participated in any impropriety," though "a review by The New York Times — including dozens of interviews and scrutiny of hundreds of pages of legal and campaign records — shows that even as her stature grew over two decades, Ms. Marks waded into ethically and legally murky territory."

Santos has attempted to place the responsibility of his financial struggles on Marks, "telling a conservative news outlet that 'the former fiduciary went rogue.'" But the longtime treasurer insists she was fooled by the embattled congressman.

Still, although prosecutors are mostly focused on Santos' wrongdoings, according to theTimes, "campaign finance experts said that Ms. Marks could face her own criminal charges if she willfully misled the F.E.C. or covered up improper behavior."