Did Fake Donors Give Eric Adams Real Money? The F.B.I. Wants to Know.

It is a type of scheme that took down New York’s lieutenant governor last year, and sank the 2013 mayoral campaign of a top Democratic contender: the use of so-called straw donors to funnel illegal contributions to candidates from secret sources.

Now, for the second time, the campaign of Mayor Eric Adams is being scrutinized for the same thing.

On Thursday, the F.B.I. searched the home of Brianna Suggs, Mr. Adams’s chief fund-raiser, as part of an investigation into whether his campaign had received illegal foreign campaign contributions from the Turkish government and Turkish nationals, disguised as coming from U.S. donors who had not actually given their own money, according to a search warrant.

And in July, six men were indicted in Manhattan in connection with a similar scheme, accused of funneling thousands to Mr. Adams’s campaign. Two brothers have pleaded guilty to a misdemeanor conspiracy charge in the case, and the news outlet The City and other organizations have found additional inconsistencies in donations to the mayor’s campaign.

Neither Mr. Adams nor Ms. Suggs have been accused of wrongdoing, and Mr. Adams has denied any knowledge of illegal contributions. But both investigations appear to be focused on whether donors who were eager to get Mr. Adams’s attention sought to mask large donations by funneling them through straw donors — and on who might have coordinated that effort.

The inquiries also raise questions about whether Mr. Adams’s campaign was properly vetting its donations to root out abuse. Andrew Yang’s rival 2021 mayoral campaign had two staff members vet donations over $100, according to a person who was familiar with the matter.

A lawyer for Mr. Adams’s 2021 campaign, Vito Pitta, said in an email that the campaign had worked to flag and investigate any questionable contributions rigorously. Mr. Pitta said the campaign had received over 10,000 donations, and had worked to match handwriting and signatures, review donors’ affirmation forms and more.

In New York City, small donations are particularly appealing. A generous matching program provides $8 in public funds for every $1 donated. That turns the maximum matched donation of $250 into $2,250, a potential enticement for anyone seeking to multiply their money.

“That’s probably the dumbest way to try to funnel money into trying to influence a candidate,” said John Kaehny, the executive director of the government watchdog group Reinvent Albany. “They’re all looked at by the Campaign Finance Board, which has the most extensive vetting and audit process in the United States. I think it’s actually a sign of amateurism.”

The city’s Campaign Finance Board examines donations closely and has pored over those to Mr. Adams’s first mayoral campaign.

Mr. Adams, a moderate Democrat and former police captain, has been involved in politics for decades, and his fund-raising tactics have repeatedly pushed the boundaries of campaign-finance and ethics laws.

As a state senator, he became embroiled in a scandal after a committee he led helped choose a provider of video-lottery machines at Aqueduct Racetrack.

And according to an indictment in the Manhattan case, a retired police inspector who worked and socialized with Mr. Adams told one prospective donor that Mr. Adams “doesn’t want to do anything if he doesn’t get 25 Gs” — a reference to the $25,000 minimum he expected for attending a campaign fund-raising event.

The early-morning search at Ms. Suggs’s Brooklyn home came as part of a broad public corruption investigation. Ms. Suggs, 25, is in the mayor’s inner circle and close with Ingrid Lewis-Martin, Mr. Adams’s longtime top aide and confidante, who has taken an active role in his campaigns and those of others.

The warrant suggested that foreign nationals had made campaign contributions through a straw donor scheme.

The warrant authorized agents to seize evidence related to payments or reimbursements made to employees of KSK Construction Group in Brooklyn, “or other persons serving as conduits for campaign contributions to the Adams Campaign originating from Turkish nationals.”

City campaign finance records reflect contributions to Mr. Adams’s first mayoral campaign from 11 KSK employees, all on May 7, 2021, totaling nearly $14,000. Nine of the 11 were in the identical amount of $1,250; most were eligible to earn matching funds for the campaign, the records show.

Ten years ago, John Liu, the city comptroller at the time, was a top contender for mayor when an investigation into his campaign uncovered a scheme to funnel money through straw donors.

Two of his former associates were convicted in the scheme in 2013, including Jia Hou, a former Liu campaign treasurer who was in her 20s. Mr. Liu, who is now a state senator representing a Queens district, was not charged, but his mayoral campaign never recovered and he finished fourth in the Democratic primary.

Last year, Brian Benjamin, New York’s lieutenant governor at the time, resigned after he was indicted in what federal prosecutors described as a brazen scheme that appeared to involve straw donors.

Mr. Benjamin was accused of accepting thousands of dollars in illegal donations from developer for his 2020 State Senate campaign and his unsuccessful 2021 bid for New York City comptroller, the indictment said. (A federal judge later dismissed bribery charges against Mr. Benjamin, but let two counts of falsifying records related to straw donations stand.)

Chris Coffey, a Democratic political strategist and Mr. Yang’s campaign manager, said donors did not always understand that it was illegal to contribute money in someone else’s name.

“Donors are often oblivious to campaign finance,” he said. “They think it’s like donating to a charity where you can be reimbursed. It’s added pressure for every campaign to make sure folks know the rules.”

Whether Mr. Adams knew any details about potential straw donors to his campaign, he has given the appearance that he is open to being influenced, Mr. Kaehny of Reinvent Albany said.

“There’s a big concern that the city is for sale and that New York has gone back to the bad old days where pay to play and bribery were just a part of political life,” he said.