The FBI has begun looking into allegations that Bryon Hefner, the husband of state Senator Stanley C. Rosenberg, assaulted several men with State House connections while boasting of his influence on Beacon Hill, according to two people familiar with the inquiry.
The agents are interested in whether Hefner offered a quid pro quo to his alleged victims, using his relationship with Rosenberg — then the Senate president — to influence the chamber’s business in return for sexual favors. Rosenberg has stepped down temporarily from the top post.
The fact that the FBI is making inquiries does not mean a formal investigation is underway, or that charges will ultimately be brought. And it is unclear whether Hefner or Rosenberg, who has not been accused of any wrongdoing, is the main target of the inquiry.
A spokeswoman for the US Attorney’s office in Boston said she could neither confirm nor deny an inquiry was underway.
The federal agents’ questions come in response to a Globe story in which four men alleged Hefner assaulted them in the past few years. Three of the men alleged Hefner grabbed their genitals (two said he did so more than once), and one said Hefner kissed him against his will.
Though three of the alleged incidents took place when Rosenberg was close by, the Globe found no evidence that he knew about the assaults.
A lawyer representing Hefner, who entered an in-patient treatment facility for alcohol dependence soon after the allegations were made public, said agents have not contacted him.
“I am unaware of any federal investigation and do not see any federal interest at play,” said attorney Tracy Miner. “No agent of the federal government has sought to contact me or my client to my knowledge.”
A spokeswoman for Rosenberg said his office does not comment on Hefner, and directed a reporter to Rosenberg’s earlier statements in which he denied that Hefner had any control over the business of the state Senate.
The FBI’s questions come as a Senate inquiry is underway into Rosenberg’s conduct and “whether he violated the rules of the Senate,” according to the formal order authorizing it. The Senate Committee on Ethics is poised to announce the hiring of an independent investigator, who will conduct the inquiry. That investigator would report back to the committee.
Several of the men Hefner allegedly assaulted and others said the then-Senate president’s husband boasted of his pull on Beacon Hill, and of his influence with Rosenberg. One alleged victim, who said Hefner assaulted him twice in the fall of 2015, said he understood Hefner to be offering to smooth his dealings in the Senate in return for sex. Several people interviewed by the Globe said Hefner spoke of what “we” — Hefner and Rosenberg — were trying to accomplish on Beacon Hill.
The day after the story was published, Rosenberg said, “If Bryon claimed to have influence over my decisions or over the Senate, he should not have said that. It is simply not true.”
The veracity of Rosenberg’s claim now appears to be central to the Senate and FBI efforts.
“If federal law enforcement is involved, then it seems likely they are investigating the actions of the Senate president as opposed to merely the actions of his husband,” said Stephen G. Huggard, a partner at Locke Lord who led the US attorney’s public corruption unit between 2000 and 2004.
“Areas of investigation might include extortion, or honest services fraud, or civil rights violations,” he added. “But any of those cases would be difficult to prove, and would require evidence of facts that are not yet in the public record as to the Senate president’s knowledge or actions regarding the alleged acts of his husband.”
Defense attorney Martin G. Weinberg, who has represented many clients in corruption cases, said that to make a case against Hefner, federal prosecutors must show that “he controls Senate president Rosenberg’s office to the extent that he could . . . perform legislative acts and exchange those acts in a quid pro quo that would be the essential element of a political corruption prosecution.”
He said that such cases are far harder to make since the US Supreme Court unanimously overturned former Virginia governor Robert F. McDonnell’s public corruption conviction last June, and narrowed the grounds on which prosecutors can bring corruption cases.
Few senators approached by the Globe would comment on the inquiry on Thursday.
“I‘m not surprised the FBI is investigating this, given the serious nature of the charges,” said Senator Barbara L’Italien, an Andover Democrat who is running for Congress and was the first to ask Rosenberg to step aside during the Senate investigation.
Thursday’s news is only the latest of recent developments that have roiled their chamber since the allegations against Hefner emerged three weeks ago.
Former state senator Brian A. Joyce was indicted last week on federal charges including mail fraud, corruption, money laundering, and embezzlement.
Prosecutors allege the Milton Democrat collected about $1 million in bribes and kickbacks that he laundered through his law firm.
The news of the FBI’s questions on Hefner, coming so soon after Joyce’s indictment, left senators cringing.
“Not a pleasant situation, that’s for sure,” said one Democratic senator. “Obviously, it’s something that is” — the senator paused to find the right words — “creating discomfort.”
Another Democratic senator said the Senate had “taken a hit,” and that some in the body “are conceding that, given what has happened over the last two weeks, this is not an environment where [Rosenberg] could ever come back as Senate president.”Joshua Miller of the Globe staff contributed to this report. Globe columnist Yvonne Abraham can be reached at firstname.lastname@example.org. Follow her on Twitter @GlobeAbraham.