Dwayne Montgomery, a retired police inspector who was once friendly with Mayor Eric Adams, pleaded guilty on Monday to misdemeanor conspiracy, saying that he had directed straw donors to contribute to the mayor’s 2021 campaign.
Mr. Montgomery was indicted in July by the Manhattan district attorney’s office, accused of a scheme to funnel contributions to the campaign and to conceal the source of donations.
In his plea Monday, Mr. Montgomery, 64, agreed not to organize or host any fund-raisers or solicit contributions for a campaign for one year. In return, the district attorney, Alvin L. Bragg, said that he would recommend that Mr. Montgomery complete 200 hours of community service and pay a $500 fine.
The mayor was not implicated in the indictment and has not been accused of any wrongdoing. When the charges became public, his campaign spokesman, Evan Thies, thanked Mr. Bragg’s prosecutors for “their hard work on behalf of taxpayers.”
Mr. Montgomery, who once worked and socialized with the mayor, was indicted along with five other defendants. Two brothers who run a construction firm that was also charged in the indictment, Shahid Mushtaq and Yahya Mushtaq, pleaded guilty in October. A plea agreement signed by a lawyer for their company indicated that they would cooperate with the district attorney’s office.
There is no such language in Mr. Montgomery’s agreement and no indication he is cooperating. The seven months between the indictment and his guilty plea would have left prosecutors time to interview him. It is not known if he provided broader information about campaign finance crimes.
A spokesman for the district attorney’s office declined to comment. A lawyer for Mr. Montgomery did not immediately respond to a request for comment.
New York City’s campaign finance law was central to the conduct detailed in the July indictment.
To help candidates without access to big donors, New York City matches the first $250 of a city resident’s donation eight to one.
The indictment said the defendants tried to hide the source of large donations by funneling them through the so-called straw donors — people who make campaign contributions using someone else’s money. That let the campaign collect more city matching funds and could have helped the defendants win influence with the incoming administration. It is unclear how much public money was spent as a result of the scheme.
Mr. Adams’s fund-raising practices have drawn scrutiny from both local and federal law enforcement agencies. Straw donor schemes have been a particular focus. Last week, the news organization The City reported that such donors were used by hotel and construction executives to channel more than $10,000 to the mayor’s re-election campaign.
Mr. Montgomery’s guilty plea is likely to draw more attention to the mayor, as Mr. Adams gears up for his 2025 re-election campaign.
On Monday, Mr. Adams defended his campaign operation at a news conference, saying that, in accordance with the law, he required all donors to affirm that they were giving the campaign their own money, and that he had also hired a compliance attorney to examine donations.
“We returned back tens of thousands of donations that did not follow that muster,” the mayor said. “We did the internal scrutiny we’re supposed to do.”
He said that, after the guilty plea, Mr. Montgomery should be allowed to go on with his life, saying, “The worst day of your life does not define your life.” He said he had not communicated with his former friend since the indictment, but if he were to see him, he would wish him the best.
More broadly, the mayor’s two-year-old administration has been plagued by investigations and allegations of impropriety.
In September, Mr. Bragg indicted Eric Ulrich, Mr. Adams’s former buildings commissioner and former senior adviser, on charges of taking more than $150,000 in bribes.
The mayor’s team is also facing a federal investigation into whether the mayor’s 2021 campaign conspired with the Turkish government to receive foreign donations.
That investigation burst into public view in November, when federal agents searched the home of Brianna Suggs, 25, Mr. Adams’s chief fund-raiser, who was given the prominent position despite her youth and lack of experience.
The same day, federal agents searched the homes of Rana Abbasova, an aide in Mr. Adams’s international affairs office, and Cenk Öcal, a former Turkish Airlines executive who served on his transition team.
Days later, federal agents seized the mayor’s electronic devices, an unusually aggressive move.
Later that month, Mr. Adams announced that Ms. Suggs was no longer doing fund-raising for his campaign.
William K. Rashbaum contributed reporting.