Special counsel Robert Mueller's team has sent a subpoena to veteran writer Jerome Corsi - the first publicly known effort to compel a journalist's testimony in the Trump-Russia collusion investigation.

Corsi, whose work has been showcased for years in conservative outlets such as Human Events, World Net Daily and the InfoWars conspiracy site, says he will not fight the subpoena and plans to appear before the grand jury on Friday.

The subpoena is a not-so-subtle reminder of just how much prosecutors, FBI agents, and the government's confidential sources who launched and sustained the Russia probe all targeted, courted and leveraged the news media.

Mueller's team reportedly wants to question Corsi about his contacts with longtime Trump friend Roger Stone and whether Stone ever asked Corsi to try to get WikiLeaks to release damaging emails on Hillary Clinton before the 2016 election ended. It's expected that Corsi will tell prosecutors he did not bite on Stone's overtures, in part because he suspected Julian Assange and WikiLeaks were monitored by U.S. intelligence after their past publications of classified U.S. secrets.

Stone is a former business partner of now-convicted lobbyist and former Trump presidential campaign chairman Paul Manafort, as well as a longtime outside adviser to Donald Trump. He recently told The Hill's new morning program, "Rising," that he fears he might be indicted by Mueller over his interest in WikiLeaks' Clinton email leaks. Stone has denied any effort to collude with Russia to swing the election to Trump.

Department of Justice (DOJ) officials declined to comment.

From the beginning of this investigation, key figures involved in it have had extensive contacts with or connections to media.

Fired FBI official Peter Strzok and his alleged paramour, former FBI lawyer Lisa Page, texted frequently about leaks in the media affecting their cases, and even suggested the FBI was behind some of those.

FBI Deputy Director Andrew McCabe was fired for lying about one media leak he authorized.

The FBI secured a FISA warrant against Trump campaign adviser Carter Page in part by citing a Yahoo News article by Michael Isikoff that, it turns out, was based on a leak from the FBI's own informant in the case, former British intelligence operative Christopher Steele, whose dirt on Trump was bought and paid for by the Clinton campaign and the Democratic National Committee.

The court that approved the surveillance warrant apparently was never told that the article was not independent corroboration but, rather, circular intelligence from the poisoned Steele tree.

DOJ notes recently provided to Congress show one of the media leaks with which Steele was involved was considered by his boss, Fusion GPS founder Glenn Simpson, to be a "hail Mary attempt" to swing the election, rather than to inform the FBI and courts. That's the sort of biased evidence the FBI should eschew, not embrace, of course.

And Strzok's own FBI communications show the FBI - after firing Steele - continued to receive versions of his now-infamous but still-unverified dossier on alleged Trump collusion with Russia. One of those was delivered to the bureau by Mother Jones magazine writer David Corn, who openly has opposed Trump's presidency.

I'm a lifelong journalist who believes in the power of the profession and its ability to serve the public with accurate reporting. But it is deeply troubling that the FBI and a federal prosecutor with unlimited resources have relied so much on the Fourth Estate's secondhand reporting to build its Russia case, when getting firsthand intelligence from original sources would far better serve the public.

Journalism, no matter how grand, remains an imperfect first record of history. Anonymous sources have motives that sometimes only a journalist knows and can't talk about. (Take, for example, Steele, whose dossier work ultimately was being funded by Democrats.)

As former FBI Director James Comey admitted in one of his last official appearances before Congress, some of the early media stories driving the Russia-Trump collusion narrative were inaccurate or based on a dossier that he himself described as mostly salacious and unverified.

Yet, the greatest danger in this prosecutorial obsession with treating news media as evidence is to the freedom of the press itself.

Whether forced or unwitting, journalists never were intended in the Founding Fathers' minds to be state's witnesses on a regular basis, in part because of the chilling effect such collusion can have on a news outlet's ability to be viewed as impartial, independent arbiters of truth.

The more the line is blurred between an independent media and government prosecutors, the more one of the essential checks and balances of democratic freedom is eroded. If journalists continue to be used as arms or evidence of the state, the American people will view the profession as less independent; sources will be more fearful to talk with reporters and thereby risk exposure.

The consequences of this blurring are heightened by an incident in the Russia case that I fear has not received enough attention.

In April 2017, DOJ and FBI lawyers led by Andrew Weissmann - now Robert Mueller's top deputy, but then a senior fraud prosecutor inside the DOJ - agreed to meet with an award-winning team of Associated Press reporters. The team produced the 2016 story that exposed Manafort's secret foreign lobbying for Ukraine and suspected money laundering, a story that led to Manafort's demise as Trump campaign chairman.

Bruce Ohr, another DOJ lawyer who appears to have been a freelance source for the FBI in the Russia case, was scheduled to attend the AP meeting but failed to show, I have been told.

According to my sources, each side entered the meeting with vastly different motives.

DOJ and FBI prosecutors hoped to persuade the reporters to turn over some Ukraine evidence on Manafort that the government didn't have, or at least to identify a source who could lead the feds to the information. The reporters made clear beforehand that they would never do such a thing but the government proceeded with the meeting anyway.

The reporters came hoping to confirm sensitive law enforcement information. And they left with corroboration about some of Manafort's bank accounts, as well as confirmation that federal prosecutors were secretly investigating Russian organized crime through their office in Brooklyn.

The exchanges between AP and DOJ also unwittingly prompted a new witness to come forward to the government. She got the names and contacts for the prosecutorial team as a result of the AP stories.

DOJ's two-step with the AP - along with the FISA applications and the Corsi subpoena - suggest that either the government is getting lazy and using journalists as a shortcut to evidence, or that it has, in the Russia case, lacked the sort of corroboration needed to proceed forcefully.

Neither reason is particularly comforting to those, like me, who view an independent media as essential to democracy.

John Solomon is an award-winning investigative journalist whose work over the years has exposed U.S. and FBI intelligence failures before the Sept. 11 attacks, federal scientists' misuse of foster children and veterans in drug experiments, and numerous cases of political corruption. He is The Hill's executive vice president for video.