Edward B. Johnson, who as a Central Intelligence Agency officer travelled into Iran with a colleague to rescue six American diplomats who fled the 1979 US Embassy takeover in Tehran, has died, the CIA confirmed on Monday. He was 81.

Johnson's identity for decades had been hidden from the public, with him known only by the pseudonym "Julio" after fellow CIA officer Antonio "Tony" Mendez published a book recounting the operation.

The 2012 Academy Award-winning film Argo, directed by and starring Ben Affleck, didn't include the second man on the team.

Yet, a painting at the CIA's headquarters in Langley, Virginia, offered a faceless acknowledgement of Johnson's existence. And in 2023, the CIA itself revealed Johnson's identity in a podcast highlighting the agency's work to free the diplomats hiding at the Canadian ambassador's residence in Tehran.

"Working with the six — these are rookies," Johnson recounted in an interview aired by the podcast.

"They were people who were not trained to lie to authorities. They weren't trained to be clandestine, elusive."

Many specifics about Johnson's professional life as a spy remained vague, as much of what was known about him publicly came from the CIA podcast first identifying him, called The Langley Files.

Johnson, who went by "Ed", described coming to the CIA after serving as an infantryman in the US Army.

Johnson served in the CIA's Office of Technical Service overseas at the time of the hostage crisis.

It began when Islamist students came over the fence at the sprawling US Embassy compound in downtown Tehran on November 4, 1979. While initially planned to be a sit-in like a previous storming, it soon became a 444-day hostage crisis.

Six US Embassy employees, however, had slipped away amid the chaos.

They ended up in the home of Canadian Ambassador Ken Taylor. Several plans came and went before US President Jimmy Carter agreed to what became known as the Canadian Caper — posing the officials as part of a Canadian film crew scouting locations for a fake, knock-off Star Wars film called Argo.

Armed with Canadian passports, Mendez pretended to be an Irish filmmaker while Johnson was "an associate producer representing our production company's ostensible South American backers", Mendez later recounted in an internal CIA document.

He described Johnson as having "considerable exfiltration experience" during the Cold War with the Soviet Union, without elaborating.

Landing in Tehran on January 25, 1980, the men used a local map to try and find the Canadian Embassy. They ended up at the Swedish Embassy — just across the street from the American Embassy, patrolled by armed students.

A local embassy guard didn't understand them, as neither man spoke Iran's Farsi language — a conscious decision made the CIA not to raise suspicions as their Farsi-language experts might be recognised.

Then one of the student revolutionaries walked over. As a conversation progressed, the men realised the student spoke German after studying abroad for a year. Johnson ended up getting written directions from the student, who even hailed a taxi for them and refused a tip.

"I have to thank the Iranians for being the beacon who got us to the right place," Johnson said.

The men ended up with the six Americans, providing them scripts, props, fake histories and training on how to pretend to be a film crew. Johnson and Mendez worked on final preparations on the passports and exit slips, the scene represented in the painting at CIA headquarters.

The biggest thing I think we did was to was to convince them that you can, you can do it — as simple as that," Johnson remembered.

On January 28, 1980, the CIA officers and the six Americans flew safely out of Tehran on a Swissair flight. Both Johnson and Mendez received the CIA's Intelligence Star, its second-highest award for valour, for the operation.

He retired from the CIA in 1995 and worked as a contractor while exploring a passion in photography, his family said.

Johnson died August 27 in his sleep in Virginia after suffering from pneumonia, the CIA said.