Snitches, moles, spies, whistleblowers. Government informants are an age-old investigative tool that's as much a part of the FBI's 110 years of history as J. Edgar Hoover or its Ten Most Wanted Fugitives list.
In the case of— identified by several news outlets as an American professor living in Britain — to ascertain whether Mr. Trump's campaign aides accepted help from the Russian government to sink Hillary Clinton's presidential ambitions. That jury is still out, with a special counsel appointed to investigate.
In the meantime, Mr. Trump and closely aligned Republicans in Congress have flipped the tables on the politically damaging Russia probe by— this time into whether the FBI spied on his presidential campaign in its own bid to sway the 2016 election.
"Follow the money!" Mr. Trump declared in a tweet late Monday, using an expression his critics use to discuss the Russia probe. "He was only there to spy for political reasons and to help Crooked Hillary win," Trump later added.
CRAZY? MAYBE NOT
The FBI has successfully investigated big-city mobsters, the Ku Klux Klan and domestic terrorists. But it has also probed the work of Rev. Martin Luther King Jr., Malcolm X and the Beatles' John Lennon.
Claiming that the civil rights movement was under communist influence and a threat to national security, Hoover's FBI closely monitored King and others with surveillance, informants and wiretaps. At one point, the head of the FBI's intelligence operations told a congressional committee that King was subjected to the same tactics as Soviet agents and, "No holds were barred."
The secret recording campaign failed to prove that King was a communist, but it did provide evidence of the civil rights leader's extramarital affairs — information that could have been used by his political opponents in government.
Since Hoover's death, the FBI has enacted several reforms including 10-year term limits on its director and new rules about domestic investigations intended in part to insulate the agency from politics.
HAVING SAID THAT ...
The mere existence of a government informant in an investigation doesn't mean a probe is tainted. It's a legal and widely accepted practice that's hardly a secret. And Mr. Trump's accusation that the FBI "planted" a source on his campaign doesn't stand up to scrutiny.
The agency itself addresses the practice on its web site, noting "special care is taken to carefully evaluate and closely supervise their use so the rights of individuals under investigation are not infringed." Informants "may receive compensation in some instances for their information and expenses," the FBI writes, but they aren't considered employees.
The agency seemed acutely aware of the political pitfalls of investigating Trump's campaign, keeping it under wraps in its early stages and, according to reports, sending a longtime source to question lower level aides.
THE FINE PRINT
While legal, employing an informant is tricky tradecraft. Government informants often have sketch dealings and their own agendas.
In the 1960s, it was New York mobster Joe Valachi who peeled back the inner workings of the crime families who employed him. In the 1980s, Henry Hill became the FBI's prized informant on the mob before disappearing into the Witness Protection Program, his life later portrayed in the film "Goodfellas."
According to news reports, the FBI informant on the Russia investigation was a longtime U.S. government insider tied to the 1980 "debategate" scandal in which aides to Ronald Reagan obtained documents Jimmy Carter was using to prepare for a presidential debate.
WHERE WE GO FROM HERE
In Mr. Trump's corner are several House Republicans who are demanding access to the FBI's closely guarded secrets in the Russia probe, including details on the FBI informant. "Let's cut through the recalcitrant bureaucracy, get the truth, and hold people accountable!" tweeted GOP Rep. Ron DeSantis of Florida.
Top FBI and Justice Department officials have already agreed to meet with congressional leaders and "review" highly classified documents in the case. Also, Deputy Attorney General Rod Rosenstein said the Justice Department's inspector general will look into whether any surveillance was politically motivated.
But DeSantis and other Trump supporters, including Rep. Lee Zeldin of New York and Mark Meadows of North Carolina, are suggesting that might not be good enough. They want their own special counsel to investigate misconduct at the FBI and Justice Department under President Barack Obama — a tactic that would flip the political narrative back to Obama and Clinton and energize conservative voters ahead of this fall's midterm elections.
THE BOTTOM LINE
Conservative pundits say liberals would be outraged had the FBI put Obama's campaigns under surveillance. Liberal pundits counter that conservatives would be outraged if Clinton's campaign aides sought or accepted the help of the Russian government ahead of the election, and the FBI ignored it.
All of this puts pressure on special counsel Robert Mueller to conclude his investigation in what has become the most politically charged atmosphere in Washington in decades.
"Spying on campaigns is extraordinary. Mueller better have the goods," tweeted Ari Fleischer, the White House press secretary under President George W. Bush, on Tuesday.