Solomon confirmed to POLITICO that Toensing and diGenova “have been my lawyers for a very long time, along with other lawyers across many different law firms.” Solomon said he used Toensing and diGenova “for libel review, to help review book and movie offers, and to do personnel contracts.”

The arrangement demonstrates how interconnected the cast of characters at the heart of the Democrats’ impeachment inquiry has become, and raises new questions about legal privileges that could help shield key players from scrutiny.

“It raises very serious questions about whether these individuals are trying to use a lawyer-client relationship to hide communications involving illicit activities,” said Ryan Goodman, a law professor at New York University.

Solomon pushed back on that, arguing that he hired the pair “years ago” and would have had to have known then that the Ukraine scandal would evolve into legal fights and impeachment proceedings if he were only using them as a shield.

Toensing and diGenova also represent Dmitry Firtash, a Ukrainian gas magnate who lives in Vienna and is fighting extradition to the U.S. on bribery charges. Firtash paid the lawyers $1 million to uncover dirt on Joe Biden and to win help in his legal case from Trump’s personal lawyer Rudy Giuliani, according to Bloomberg News.

Solomon was the first to report on an affidavit obtained from Firtash by his lawyers, Toensing and diGenova, who are also Solomon’s lawyers.

The lawyers’ son, Brady, joined DOJ’s Office of Legal Counsel in June as a senior counsel.

The privilege issue came up most recently in a New York court on Wednesday, when a lawyer for the recently indicted operative Lev Parnas said the White House might invoke executive privilege over evidence collected in the campaign finance investigation. That is because Giuliani was representing Parnas and Trump at the same time, said the lawyer, Edward MacMahon Jr.

“He was working for Mr. Giuliani and Mr. Giuliani was working for the president of the United States,” McMahon told the judge, U.S. District Court Judge Paul Oetken.

Solomon, a former op-ed columnist and executive vice president for The Hill who recently left to launch his own outlet, has written extensively about Hunter Biden’s activities in Ukraine and about Marie Yovanovitch, the veteran ambassador who was abruptly recalled in May amid a campaign by Trump’s allies—including Giuliani—to remove her. DiGenova and Toensing have appeared frequently as guests on Hill TV.

A series of articles Solomon published about Ukraine were mentioned in an anonymous complaint by an intelligence community whistleblower, which characterized Solomon’s work as part of the “circumstances leading up to” Trump’s July 25 call with Ukrainian President Volodymyr Zelensky. In that call, Trump asked Zelensky to investigate the Bidens and “get to the bottom of” Ukraine’s alleged interference in the 2016 election.

Solomon, who is now a Fox News contributor, also featured in documents the State Department’s Inspector General gave Congress earlier this month that revealed a campaign to smear Yovanovitch and the Bidens.

Included in the roughly 50-page packet was an email from Solomon to Toensing, diGenova, and Parnas previewing an article he’d written that was not yet published. The story claimed that the Obama administration had directed Ukrainian prosecutors to drop an investigation into a group “co-funded by both the Obama administration and the liberal megadonor George Soros.”

After that email became public, Solomon claimed he was simply fact-checking the piece before it was published. But Toensing, diGenova, and Parnas are not mentioned in the article, raising the possibility that the trio, who had been working to find evidence of wrongdoing by the Bidens in Ukraine, had been working directly with Solomon on the story.

Ukrainian interference in the 2016 election and corrupt pressure by the Obama administration on Ukrainian prosecutors are not the first unsubstantiated theories pushed by Toensing and diGenova that Solomon has advanced in his columns.

Solomon also wrote extensively about the Uranium One controversy, which alleged a link between a 2010 sale of U.S. uranium supplies and donations to the Clinton Foundation.

In October 2017, Solomon was the first to report on an informant who accused former secretary of state Hillary Clinton of helping a Russian company improperly obtain uranium mining rights—an informant being represented at the time by Toensing.

In 2017, then-attorney general Jeff Sessions appointed U.S. Attorney John Huber to look into the Uranium One matter under public pressure from President Trump, but he has yet to produce any findings.

DiGenova’s ties to William Barr, Sessions’ successor as attorney general, go back years.

In a striking moment from one of his HillTV appearances, diGenova defended Barr’s handling of the report by special counsel Robert Mueller.

“Don't you dare suggest that Bill Barr is a liar,” told the host. “I’ve known him for 30 years. He's one of the finest lawyers this country has ever produced.”

During his first stint as attorney general, Barr tapped diGenova -- who was then a former U.S. attorney for the District of Columbia -- as an independent counsel to review allegations that State Department officials improperly accessed Bill Clinton’s passport records.

In 2017 Barr, before his return as Trump’s attorney general, shared his view with New York Times reporter Peter Baker that “the predicate for investigating the uranium deal” -- a reference to the Uranium One controversy promoted by diGenova and Toensing -- “is far stronger than any basis for investigating so-called ‘collusion.’”

Those ties can apparently only take the lawyer pair so far, however. According to a recent account in the Washington Post, diGenova and Toensing met with Barr to discuss Firtash sometime after becoming his attorneys.

Barr declined to intervene in the Firtash case, the Post reported.