'World’s most successful spy’ who helped Putin seize power & fed US secrets to Russia for 10 YEARS
A DOUBLE agent dubbed "the world's most most successful spy" was instrumental in helping Vladimir Putin seize power - and his identity STILL remains a mystery decades on.
Known simply as "The Fourth Man", the mole was one of several Soviet spies who managed to infiltrate the heart of the US intelligence services.
But unlike most who were eventually dug out, this mysterious spook has never been identified - making it one of the biggest mysteries in all of espionage.
Russia's spies at this time left the CIA paralysed and blind - with no trusty intel being fed to them on the sudden rise of the brutal Vlad.
With this gap, former KGB man and mafia enforcer Putin was able to consolidate his power and set the scene to take control of Russia.
"The Fourth Man" compromised the identities of Russian spies working for Washington DC and leaked troves of sensitive CIA data.
Ex-CIA agent Robert Baer told The Sun Online the actions of the spy at this time "could have changed history".
It is thought that perhaps if "The Fourth Man" had been weeded out - US intelligence would have been able to identify the threat from Putin and warn the Kremlin.
He said all conversations between then US President Bill Clinton and then Russian leader Boris Yeltsin were leaked to Putin and the KGB.
It's claimed Vlad then helped use this to intimidate Yeltsin, who was the first Russian leader after the collapse of the Soviet Union, and seize control in 1999.
Putin usurped Yeltsin as the president of the Russian Federation and began a stunning reform of Kremlin politics that would change the country forever.
"Was there any point that Clinton could have talked Yeltsin into finding somebody else other than Putin, if we had known who Putin was and what he was doing? Could we have changed history?" explained Baer.
"I think there probably was. At that point, if we would have understood that the KGB was embedding itself into the Russian government, preparing a takeover in 1999, was there a possibility to head this off?"
According to Baer, the Russian spies who infiltrated the CIA in this period were known as "The Cambridge Five but only worse" - referencing Soviet spy ring who infiltrated in UK from 1930s to 1950s.
And while the US caught a number of spies, there were still leaks that could not be explained - leading them to begin the hunt for the mysterious "Fourth Man".
Baer told The Sun Online: "There was a Fourth Man - simply look at the evidence.
"No one doubts it, and the fact the FBI has been pursuing this for 25 years actively.
"The people and the USSR branch and all the rest all agree there was a Fourth Man.
"I have no doubt about that, the question is who was it? Some people believe he’s dead, some people believe there was a fourth and a fifth man. Was he the most brilliant spy ever?"
In a desperate bid to weed out them out, the agency and FBI created the Special Investigations Unit (SIU) in May 1994 that was led by seasoned intelligence chief Paul Redmond and four other officers.
Within six months, the highly-secretive unit was "shutdown" and its officers shipped off to dead-end jobs.
What they discovered would have profound implications for US intelligence for years to come.
The 1980s was a devastating time for US intelligence agencies.
Despite being on the cusp of winning the Cold War, the CIA and FBI were rocked by a wave of damning defections of top officials to Moscow and a number of high-profile infiltrations by Kremlin-backed spies.
Among those were CIA officers Edward Lee Howard and Aldrich Ames and FBI agent Robert Hanssen, who, together, helped identify, arrest, imprison and execute agents working for the US during the Cold War.
Desperate to clear the decks, both agencies established the SIU and tasked it with solving a list of "anomalies" that couldn't be explained away by dodgy acts committed by Howard, Ames or Hanssen - namely an event known as the "'85-'86 losses" of Russian agents.
CIA officers Laine Bannerman, Diana Worthen, and MaryAnn Hough and FBI analyst Jim Milburn began their highly secretive mission to find and weed out what they thought was "The Fourth Man".
"They went as far back as 1983 and looked at the timeline at when Ames was in the job, when Howard was in the job, and it just didn’t fit. There were these compromises that they just couldn’t be responsible for," Baer told us.
The ex-CIA spook turned writer said the SIU quickly noticed how a Pentagon request for information on Russian weapons had been leaked to Moscow.
"It was apparent that list was immediately leaked to the Russians who then proceeded to feed disinformation into the CIA, which the CIA caught on to and so did the Pentagon," said Baer.
The team was also tipped off about "The Fourth Man" by a trusted Russian spy.
They also noticed the Russians were deliberately flooding their Washington DC embassy with officers in a bid to overwhelm CIA surveillance teams in a tactic known as "starbursts".
Their aim was to clear the way for a KGB agent to meet with the mole without CIA surveillance on their backs.
But the biggest give-away was the ousting of the Soviet agent and former KGB colonel Oleg Gordievsky, who was suddenly recalled to Moscow from London in May 1985, drugged and interrogated.
"The real anomaly was Gordievsky," Baer explained.
"It was the considered opinion of the FBI and CIA that it was not Ames who gave up Gordievsky.
"It was somebody months and months before who had given his identity to the Russians."
After weeks of investigating, the undercover team put together a list of six to seven suspect and conducted in-depth profiling on each of their careers.
"When they got to the bottom of the list," Baer said, "they found it was [the head of the SIU] Redmond."
FROM RUSSIA WITH LOVE
The "Cambridge Five but worse
Together they helped identify, arrest and kill CIA agents in Moscow during the 1980 and 1990s.
Howard was the first CIA operative to defect after growing disgruntled over being fired and passed on classified information to a KGB contact in Europe.
He defected to a Soviet embassy in Helsinki, Finland, in 1985. On July 12, 2002, he was found dead at his home in Russia reportedly from a broken neck after a fall from his home.
Ames compromised more CIA agents than any other officer in history and helped foil at least 100 intelligence operations before his arrest in March 1993.
The CIA agent spoke fluent Russian and regularly met Soviet embassy officials who paid him thousands of dollars for the information he passed on.
His colleagues grew suspicious after he purchased a luxury $50k Jaguar and $540k home in Arlington, Virginia, which he in paid cash, on his meagre $60k-a-year salary.
He is currently serving a life sentence at the Federal Correctional Institution in Terre Haute, Indiana.
Hanssen, a former FBI agent, was the most prolific spy. He fed secrets to the Soviets from 1979 to 2001 in what the US Department of Justice dubbed "possibly the worst intelligence disaster in US history".
Hanssen was arrested in February 2001 after being caught leaving a package of highly classified material at a dead drop site. He pled guilty to espionage charges and was sentenced to 15 consecutive sentences of life in prison.
The team handed over their findings to CIA bosses in December 1994.
"They knew this was not airtight information but what they really wanted to do is not indict Redmond or somebody else, what they wanted was to open the investigation and look into things such as financials, travel, because it couldn’t all be in any way considered evidence until that was done," Baer explained.
"They never directly said Redmond but they just looked at the matrix and the profile and said they couldn't come to any other conclusion."
But when Bannerman, Worthen, and Hough and Milburn dropped their report into the laps of their bosses hoping they'd make the right decision, they were proven harshly wrong.
Baer said: "What occurred was instant retaliation against them.
"They were moved out of their job, they were given make-work and unimportant jobs. It was clear their careers were over."
The SIU was disbanded and taken over by the FBI, meanwhile Redmond stepped down and was never charged.
Years later, Bannerman would go on to work with Baer, who recently wrote a book on the mystery infiltration called The Fourth Man: The Hunt for the KGB's CIA Mole and Why the US Overlooked Putin.
It's not the first time the "Fourth Man" theory was discussed in public.
The Main Enemy, published in 2003 by James Risen and former CIA officer Milt Bearden, has US officials on the record believing there was another rouge agent on the loose inside the US' top spy body.
Baer said members of the SIU team are coming forward now because they "didn't want the guy to get away with it".
But Baer says without more information, it's impossible to say for sure that Redmond was the mole that plagued the CIA for decades.
"You’re innocent till proven guilty and there’s no smoking gun here in this story," he said.