Federal investigators leading an inquiry into Senator Robert Menendez of New Jersey, the powerful Democratic chairman of the Foreign Relations Committee, subpoenaed records this week from at least one longtime New Jersey mayor and state senator, Nicholas Sacco, several officials said.
The subpoena was delivered at about 6:30 a.m. on Wednesday, the day after a momentous election in Hudson County, a famously sharp-elbowed political proving ground in northern New Jersey where Mr. Menendez cut his teeth as a lawmaker.
The request for the documents made clear that Mr. Sacco, a Democrat who has served in the State Senate for 30 years and on Tuesday was re-elected to his ninth term as mayor of North Bergen, N.J., was not a target of the inquiry, according to his spokesman, Phil Swibinski.
Mr. Sacco will “cooperate fully and provide any requested information, as he would with any law enforcement inquiry,” Mr. Swibinski said in an email.
“Mayor Sacco has been assured that he is not a target of the investigation and was approached only as a potential witness,” added Mr. Swibinski, whose public relations firm also does work for the state’s Democratic Party.
There have been few outward signs of movement in the federal investigation of Mr. Menendez since an initial blitz of subpoenas became public in October. And Mr. Menendez, 69, has continued to raise funds at a brisk clip for his expected run next year for a fourth term in the United States Senate.
But even while amassing more than $1 million in donations during the first quarter of the year, Mr. Menendez was also paying large bills related to the investigation, according to Federal Election Commission records filed last month.
Michael Soliman, a spokesman and close political adviser to Mr. Menendez, has said that the senator planned to create a legal-defense fund to pay for costs associated with the investigation, which is being led by prosecutors in the United States attorney’s office for the Southern District of New York.
“Senator Menendez is confident that this official inquiry will be successfully closed,” Mr. Soliman said last month. “But as it is still unresolved, he will be opening a separate legal-defense fund so as not to drain any further campaign funds.”
The nature and extent of the investigation into Mr. Menendez is unclear, but it is related at least in part to a New Jersey start-up company, IS EG Halal, which over the course of a year became the sole entity authorized to certify that halal meat imported into Egypt from anywhere in the world was prepared according to Islamic law.
Wednesday’s subpoena seeks records related to the halal enterprise as well as information about a bill that Mr. Sacco has twice sponsored in Trenton with Senator Brian Stack, according to a person familiar with the details of the subpoena, who requested anonymity because they were not authorized to discuss the document publicly.
The subpoena specifically asked for any correspondence about the bill from Mr. Menendez; his wife, Nadine Arslanian Menendez; or Fred Daibes, one of the region’s most prominent developers, who pleaded guilty last year to a federal banking crime, the person said.
Mr. Soliman declined to comment on the subpoena. Mr. Stack, who is also the mayor of Union City, N.J., a job Mr. Menendez held in the 1980s and early ’90s, did not return calls.
The bill, the Palisades Cliffs Protection and Planning Act, has not advanced in the Legislature but would limit the height of development projects near the Palisades, along the Hudson River. The legislation faced opposition from construction trade unions and some developers.
Mr. Daibes’s negotiated plea agreement required no prison time. And this month, Mr. Daibes, an Edgewater, N.J.-based builder whose projects transformed the Hudson River waterfront, was the subject of a scathing 83-page report from New Jersey’s Commission of Investigation.
The commission found that Mr. Daibes provided direct and indirect financial benefits to elected leaders in Edgewater, and that he held outsize influence on policy decisions in the borough. Neither he nor his lawyer could be immediately reached for comment.
Mr. Menendez has maintained from the start that he would cooperate fully with any investigation. And F.E.C. reports indicate that his lawyers have been doing so.
Since January, his campaign committee has paid $127,000 to Winston & Strawn, a law firm led by Abbe Lowell, who represented Mr. Menendez during a two-month bribery trial in 2017, the records show. The case ended in a mistrial after jurors could not reach a unanimous verdict, and prosecutors declined to retry Mr. Menendez after a judge dismissed many of the charges.
Mr. Menendez’s campaign committee also paid $48,000 to Schertler Onorato Mead & Sears, a Washington law firm, and $55,000 to Haystack ID, a company enlisted last year by the Trump Organization to respond to subpoenas from New York’s attorney general after former President Donald J. Trump was held in contempt of court for failing to do so.
Representatives from Haystack and the two law firms did not reply to calls or emails.