Two days after then-acting FBI Director Andrew McCabe formally put President Trump under criminal investigation in May 2017, bureau officials reached out to the author of the controversial "Steele dossier" for more information, even though they had fired him for misconduct six months earlier.

Text messages and congressional testimony transcripts reveal that McCabe’s “Russia team” re-established direct contact with ex-British spy Christopher Steele to build a case against the president for espionage and obstruction of justice after Trump had fired FBI Director James Comey on May 9, 2017.

Comey had previously described the dossier – opposition research alleging Trump-Russia ties that was paid for by the Clinton campaign – as “salacious and unverified.” The FBI had severed ties with Steele in November 2016 due to behavior that convinced his handlers he was not a trustworthy source.

Former federal prosecutors and investigators described the move to RealClearInvestigations as "desperate." They also said the FBI’s decision to suddenly re-engage with a discredited confidential source raises fresh questions about the evidentiary grounds on which the FBI opened an unprecedented probe targeting the president.

“It suggests that McCabe lacked evidence to make an espionage case against Trump and was desperate to find it — even if that meant going back to the same unreliable source of still-unverified dossier dirt,” former federal prosecutor Solomon L. Wisenberg said.

While noting that there are not only Justice Department rules but also federal laws against opening groundless investigations, they warned that if the nation’s top police force can investigate and spy on a president without hard evidence of criminal behavior, they can do it to anyone. “It’s pretty clear that Comey’s firing is what prompted McCabe’s fury," Wisenberg said.

McCabe, who ran the FBI after the president fired Comey, maintains he had sufficient grounds to authorize two investigations of the president himself — including whether he was personally acting on behalf of the Russian government and whether he was impeding the ongoing investigation into Russian interference in the 2016 election.

In a series of recent television interviews promoting his new book, "The Threat," McCabe said his decision to investigate Trump as a Russian asset was based on public information, not secret intelligence or any smoking-gun evidence tying Trump to the Kremlin.

Related: McCabe Investigated Not Just Trump but Sessions Too

Prosecutors and investigators interviewed by RCI said none of the information made public should have been enough to launch an FBI probe. But the Comey firing reportedly will be part of an obstruction-of-justice and corruption inquiry announced on Sunday by the new Democratic House Judiciary Committee Chairman, Jerrold Nadler, which could result in Trump's impeachment.

In the days following Comey’s firing, McCabe quickly assembled his “Russia team” of investigators, led by Peter Strzok, who was accused of anti-Trump bias when he was later fired by the bureau. McCabe says his team recommended he order a full investigation of the president, which he says he approved on May 10.

On May 12, two days later, the FBI sought to reconnect with its old informant Steele.

The overture was made through senior Justice Department official Bruce Ohr, whose wife, Nellie, worked for Fusion GPS, the opposition research firm paid by the Clinton campaign to dig up dirt on Trump. Fusion GPS, in turn, had paid Steele, a former British spy, to create the dossier. Ohr had served as a steady go-between channeling anti-Trump research from Fusion GPS and Steele to the FBI throughout the presidential campaign and the first year of the Trump presidency. Republican Rep. Mark Meadows asked Ohr about these contacts during a closed-door congressional hearing last August, transcripts of which were released late last month.

"Did the FBI ever encourage you to reach out to try to get additional information from Chris Steele?” Meadows asked Ohr.

"Yes, there was one occasion,” Ohr replied. "On one of the occasions when I talked to the FBI to tell them I got a call from Chris Steele, they said, ‘Oh, next time you talk with him, can you ask him if he’s willing to meet with us?’ And I conveyed that back to Chris Steele."

The request was made on Friday May 12, when Ohr met with Strzok’s deputy on the Russia team – special FBI agent Joe Pientka – according to FBI documents. The next day Ohr passed the request on to Steele. Ohr and Pientka met again for an interview the following Monday, May 15. In a text message to Ohr sent that same day, Steele agreed to re-engage with the FBI.

Steele: "B[ruce], having now consulted my wife and business partner about the question we discussed on Saturday, I’m pleased to say yes, we should go ahead with it. Best C[hris]"

Ohr: "Thanks! I will let them know and we will follow up."

At the congressional hearing, Rep. Jim Jordan (R-Ohio) questioned Ohr about the May 15 text to Steele: “So you have asked him will he re-engage with the FBI?” And Ohr responded: “Yes.”

Ohr continued to debrief Steele on behalf of the FBI through late November 2017, transmitting his information to Pientka and other agents, even though Special Counsel Robert Mueller was appointed to take over the Russia collusion case on May 17, 2017. “At some point during 2017, Chris Steele did speak with somebody from the FBI,” Ohr testified. Mueller’s investigators have also interviewed Steele.

Law enforcement sources described the FBI’s move as a "Hail Mary" attempt to collect more information on Trump to help justify making him a formal suspect in the Russia investigation. Steele had provided the foundation, tenuous as it was, for earlier investigations of Trump campaign advisers.

The FBI struggled to identify Steele’s anonymous sources and sub-sources and corroborate their sensational accusations, and still had not succeeded in doing so at the time McCabe opened the case on Trump. In fact, internal FBI documents show the bureau graded the credibility of the Steele dossier as low.

Michael Biasello, a 25-year veteran of the FBI who spent 10 years in counterintelligence, agreed that McCabe lacked a case against Trump. "What McCabe did is outrageous,” he said, "and McCabe as a lawyer should have known better.”

Biasello noted that two months after ordering the probe of Trump, McCabe also signed an application to renew a surveillance warrant to electronically spy on a former foreign policy adviser of Trump. The July 2017 warrant to surveil Carter Page, which may have collected “incidental" communications with White House aides, relied heavily on information provided by Steele, which the FBI failed to tell the secret FISA court was uncorroborated and paid for by the Clinton campaign.

McCabe has testified that without the dossier, the original FISA warrant could not have been obtained by the FBI in October 2016. Ohr testified he first warned McCabe of Steele’s anti-Trump bias during an August 2016 meeting in the then-deputy director's office. In British court papers, Steele himself confessed that his dossier was “unverifiable” and could never be used in a court of law.

“McCabe appears to have violated the law to obtain evidence as part of an effort to subvert a sitting president,” Biasello asserted, adding that he may have also engaged in a "criminal conspiracy" to remove the president from office. On May 16, 2017, McCabe discussed trying to oust Trump via the 25th Amendment with Deputy Attorney General Rod Rosenstein. The two also talked about "wiring the president" -- secretly tape-recording his conversations. (Rosenstein has confirmed the exchange, but says he was being sarcastic -- as a way of showing how absurd he found the conversation.)

The FBI did not respond to requests for comment. Lawyers for McCabe also did not answer requests seeking comment.

An irony is that McCabe was later fired for much the same offenses as Steele's: leaking and lying about it. Steele was dismissed Nov. 1, 2016 for unauthorized disclosures to the media, including Mother Jones and Yahoo News, and found to have concealed and lied to the FBI about them. Attorney General Jeff Sessions fired McCabe last March after the Justice Department’s inspector general found he had repeatedly lied under oath to investigators about leaking information to the press regarding the ongoing Clinton Foundation case.

McCabe, now under federal criminal investigation for those alleged offenses, has insisted he made the decision to investigate the president based on facts, not politics, and that Rosenstein and the Justice Department accepted his reasons for commencing an investigation.

“We had an articulable basis to believe that a crime may have been committed or a threat to national security might exist [from the president himself],” McCabe told CNN.

Under FBI and Justice Department guidelines for opening a full investigation, agents have to first establish an “articulable factual basis," which means facts must be specified and verified. And investigators have to have a "reasonable suspicion,” as opposed to mere speculation, that a suspect committed a crime.

Former FBI special agent Mark Wauck doubts his old agency met that standard of proof: “The predication for the full investigation -- the ‘articulable factual basis’ — had almost certainly been the Steele dossier, now known to be unverified.” McCabe’s team would have had to spell out the legal basis for opening their probes of Trump in an “electronic communication,” or EC. And the EC, which establishes the investigative case file, would have had to assert that there were specific, verified facts indicating the president was a "threat to national security."

Judicial Watch, a government watchdog group, does not believe McCabe had the factual and legal grounds to target the president, and is pressing the Justice Department to release the ECs and other records detailing the legal justification for the FBI's momentous investigations.

Judicial Watch President Tom Fitton maintains that McCabe’s targeting of Trump without proper evidence was an “abuse of power,” and may also have been illegal.

“Mr. McCabe had zero good-faith basis to initiate any investigation of President Trump,” Fitton said. "And his authorization of a secret counter-intelligence investigation of a sitting president is an astonishing violation of the Constitution, as the Justice Department is not its own branch of the government.”

Fitton said he does not buy McCabe’s argument that Trump’s firing of his boss was evidence that the president was trying to obstruct the Russia investigation. "McCabe’s suggesting he only began investigating President Trump because of the perfectly reasonable Comey firing is bull,” he said. "The Justice Department and FBI had been spying on and lawlessly investigating Trump" -- through his aides -- "for at least a year prior to Comey’s firing.”

McCabe’s own top investigators expressed skepticism that Trump conspired with the Kremlin at the time McCabe ordered the investigations of the president.

In a May 19, 2017, text message to McCabe’s counsel Lisa Page, Strzok remarked, “My gut sense and concern is there’s no big there, there” regarding collusion. Page admitted during a private 2018 congressional interview that when McCabe opened the probes, “We still couldn’t answer the question [of whether Trump conspired with the Kremlin]. … It still existed in the scope of possibility that there would be literally nothing” to connect Trump with Russia.

This article originally appeared at RealClearInvestigations.