STOCKHOLM - Forty years ago in a Stockholm bank, a psychiatric phenomenon was born.

It is one of the most emblematic syndromes in psychiatry literature, and if there is anyone in the world who knows exactly how the Stockholm syndrome works, it is the man himself: Jan Erik Olsson. “I remember every detail, every single instant, every word,” says Olsson, speaking four decades later from the Swedish capital. “But I still can’t explain how it could have happened.”

On Aug. 23, 1973 at 10:15 a.m., 32-year-old Olsson stormed into the Kreditbanken on the central Norrmalmstorg square, pulled out a sub-machine gun, and started firing into the air, while screaming "The party's starting! Everyone, face down!" He took four employees hostage, demanding 3 million Swedish crowns ($730,000) and the liberation of his friend from prison.

That criminal act, which would become a long, drawn-out standoff between Olsson and the police, marked the beginning of what American psychiatrist Franck Ochberg would define as “Stockholm syndrome,” the irrational attachment between victims and kidnappers that can develop during the course of a sequester.

The Stockholm hostage crisis, which lasted six days, was the first crime story to be televised in Sweden and had unexpected — and rather spectacular — consequences. Very quickly, in fact, the fear in the eyes of the hostages was transformed into something rather more complex.

On Day 3 of the standoff, Olsson and the hostages took refuge further inside the bank to distance themselves from the police outside. Until then, he had been wearing a wig with brown cream on his face (aiming to look like an Arab terrorist). "I took off the wig and started to talk," Olsson recalls. “We talked about our lives, our dreams, our fears. I told them about my children.”

The first sign that things were starting to change was when one of the hostages asked permission to go to the toilet. “I was tired,” Olsson says, “I knew the toilets were near where the police were, I knew that he would escape, but nevertheless I told him ‘Go, but make sure you come back.’” Amazingly, the hostage did return, even though police had tried to convince him to flee.

Later in the standoff, as officers surrounded the bank, the Swedish Prime Minister Olof Palme called inside, and one of the hostages, Kristin Enmarkl, picked up. “Do you understand that I’m not scared of him, do you understand that I’m only scared of the police? Believe it or not, we’re fine here,” she said. This unexpected and incomprehensible behavior upset public opinion.

The feelings are mutual

Ultimately, the lasting conclusion to events was written by the American psychiatrist Ochberg, who defined the paradigm “Stockholm syndrome” and lifted the veil on the pathological and unfathomable attachment between captor and captive.

Used and abused, Stockholm syndrome is based on three elements, as explained by Ochberg, who has dedicated his whole life to helping kidnapping victims — from American diplomats held hostage in Iran for 444 days from November 1979 to January 1982, to survivors from the massacre at Columbine in 1999. Recently he gave evidence in the case of Ariel Castro, the accused sadistic Cleveland man who held three women captive for 10 years.

“The first element is when the victims bond their captor, which can go as far as developing into love," Ochberg explains. "The second is the inverse; when the captors returns that love and starts to care for the victim; this is why, in some cases, for the well-being of the victim, one hopes the syndrome will be triggered. And finally, the mutual contempt of both parties for the outside world.”

Normally, the psychiatrist says “it takes place suddenly, in cases where the hostages are certain that they will be killed. When they realize that they are being saved, when they are allowed to eat, sleep and go to the toilet, they feel — in spite of everything — immensely grateful, as if they were once again newborn babies, totally dependent on their mother.”

When they are finally freed, they can feel closer to their kidnapper than their family, who they may unconsciously feel has abandoned them. Austrian Natalia Kampusch, held in isolation for eight years, said she felt alienated from her parents and she cried upon hearing the news of her jailor’s death.

Other famous cases included that of Patricia Hearst, the American heiress who became a guerrilla for the Symbionese Liberation Army, or that of Giovanna Amati, victim of a kidnapping by a group from Marseilles, France. In other cases, like that of Castro, Ochberg cautions that references to Stockholm syndrome are imprecise.

Today, Olsson, a tranquil 72-year-old father of nine, who works as a part-time used car salesman, recalls that during his 10-year prison sentence, two of the hostages visited him. Even now, 40 years after the events which triggered the first studies of this curious phenomenon, he still sees his hostages occasionally, even returning to the scene of the crime.

“The same people work there now," Olsson says. "When I happen to be in Stockholm I drop by to say hello. They welcome me like a friend.”