The FBI agent credited with exposing one of the most prolific traitors in US history wishes he could have spoken to him one final time — revealing the turncoat wanted to be “James Bond” in the wake of his death.

Eric O’Neill took to Twitter, saying he regrets not asking Robert Hanssen — the former FBI agent sentenced to life in prison in 2002 for spying on America for Russia — why he betrayed his homeland.

“This closes the door on a huge moment in my life. I had hoped to confront him one last time, face to face,” the agent tweeted on Tuesday.

Hassen was found dead inside his Colorado supermax jail cell on Monday.

He was 79.

In 2001, newbie 25-year-old FBI agent O’Neill was tasked by his supervisor to spy on Hanssen after the agency was made aware he could be providing crucial US secrets to the Russians.

“I just heard that the FBI’s most damaging spy Robert Hanssen, code name: Gray Day, passed away in his jail cell today,” O’Neill wrote.

Eric O’Neill was a fresh face for the FBI when he was tasked with spying on the higher-ranking Hanssen. Twitter/Eric O'Neill

Robert Hanssen was charged with 15 counts of espionage as a result of spying for the Russians. Twitter/Eric O'Neill

“Why did you do it,” the agent responded to a user asking what he would have asked the most damaging spy in FBI history if he still had the chance.

“I would have told him that despite his crimes, he influenced my life. We can learn from anyone, even the most damaging spy in US history,” he tweeted.

Under the alias “Ramon Garcia,” Hanssen exchanged highly classified national security information to his Russian handlers from 1985 until his arrest in February 2001.

FBI agents arrest counterintelligence agent Robert Hanssen (C) near his home on Feb. 18, 2001 Getty Images

Hanssen had just placed a package of classified material in a park prior to his arrest. Getty Images

O’Neill is left with mixed emotions as he processes the death of the man who heavily influenced his path as an FBI Agent.

“He wanted to be James Bond, and he thought they’d made him a librarian,” O’Neill told The Washington Post when asked why he believes Hanssen spilled secrets.

O’Neill revealed that Hanssen was patriotic but was unpleased as an employee of the Bureau after hopes of being a field agent were replaced with being assigned to work as an analyst.

Hanssen was confirmed to be working with the Russians after O’Neill copied data off the spy’s personal PalmPilot, which provided the FBI with the location of his next dead drop for his handlers.

The bridge in the park where Hanssen would pick up and drop off packages to the Russians. Twitter/Eric O'Neill

A courtroom drawing showing US spy Robert Hanssen (L), his attorney Palto Cacheris (2nd-L), federal prosecutor Randy Bellows (2nd-R) and US District Judge Claude Hilton (R) inside the US District Courthouse in Alexandria VA, on May 31, 2001. AFP via Getty Images

The turncoat was observed by the FBI placing a package of classified material under a walking bridge in Foxstone Park, in Vienna, Va., and was arrested.

Hanssen had been using the bridge to exchange documents with his handlers since 1985.

Some of the information that Hanssen was providing to the Russians was on two KGB officers who were secretly working for Washington.

They were killed as a result of his sharing of the information.

His payment over time for his betrayal of oath and service to America was $1.4 million in cash and diamonds.

Hanssen in prison at US District Court for the Eastern District of Virginia following his arrest on Feb. 18, 2001. Polaris

Hanssen pled guilty to 15 counts of espionage in July 2001 and faced the death penalty for his crimes.

In May 2002, he was sentenced to life in prison.

On the surface, the disgraced agent portrayed himself as a hard-working father of six with a solid devotion to Catholicism with a cozy four-bedroom house in Fairfax County, Va. — about 20 miles outside of Washington, DC.

But, lurking in the underbelly of the manipulative spy was the perversion of sexually deviant activities.

Following the exposure of his acts of espionage, it was revealed that Hanssen installed a camera to record his wife during sex without her knowledge, and would invite his best friend to watch, according to CBS.

FBI agents sealing off the home of FBI agent Robert Hanssen. Getty Images

FBI agents remove evidence from the home of the veteran FBI agent on Feb. 20, 2001 in Vienna, Va. Getty Images

Hanssen also sent the same friend nude photos of his wife and was known to frequent strip clubs in the DC area where he would try to convert the dancers to become Catholics.

A psychiatrist hired by Hanssen’s lawyers examined him and revealed his sexual perversions were part of a psychological disorder.

Priscilla Sue Galey, a stripper who befriended the spy, said she was given cash, jewels, and a Mercedes-Benz by Hassen, according to The Washington Post.

Galey says Hanssen never asked for sex and was devoted to his family, revealed he even gave her a tour of the FBI’s training facility in Quantico, Va., and a laptop with a secret password.

The identification and business card of former FBI agent Robert Hanssen is seen inside a display case at the FBI Academy in Quantico, Virginia, on May 12, 2009. AFP/Getty Images

The computer, which Galey pawned off, was not recovered by the FBI and never determined if the agency owned it, but it was believed not to be.

It’s believed a motivation for why Hanssen spied for the Russians was because of money, but once his financial needs were met, it was never shared why he continued the betrayal.

“It was the thing that made him feel that he was the best at something in the world. No one was better,’ O’Neill shared. “He knew that it was going to make him immortal. And it did.”

O’Neill expressed that he wishes he could have asked Hanssen the real motive he sold his country out to the Russians. Twitter/Eric O'Neill

Letters Hanssen wrote to his Russian handlers showed the spy since he “was 14 years old” after reading a book about Kim Philby — a British intelligence officer working as a Russian double agent.

“One might propose that I am either insanely brave or quite insane. I’d answer neither. I’d say insanely loyal. Take your pick. There is insanity in all the answers,” the letter read.

It’s suspected he probably used the money to pay for his sons’ preparatory school and his daughters’ Catholic school, according to the NY Times.

Hanssen’s espionage story inspired the 2007 movie, “Breach,” starring Ryan Phillippe and Chris Cooper.

“It’s not a story about gain. It’s a story about game,” David G. Major, a former FBI counterintelligence official who knew Hanssen, told The Washington Post in 2001.