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ROME—One morning in November 2018, North Korea’s top diplomat in Italy left his embassy’s compound with his wife. He told colleagues they were going for a stroll.

Instead, the couple got into a car idling nearby and never returned. Driving the getaway vehicle that day was a member of a clandestine group called Free Joseon, people familiar with the operation say.

For the past decade, Southern California-based Free Joseon, which is dedicated to bringing down the regime of North Korea’s Kim Jong Un, has organized defections and escapes from embassies, obtained government documents, and successfully rescued the family of Mr. Kim’s exiled half brother after his murder in 2017.

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The persistent yet little-known threat has raised alarms within North Korea, dealing a blow to the regime’s carefully crafted image of stability. Free Joseon’s involvement in the defection of North Korea’s top diplomat in Italy, Jo Song Gil, hasn’t been reported before. Mr. Jo and his wife are now in hiding in an undisclosed Western country, according to people familiar with events.



North Korea has deployed assassins to target members of the group, according to U.S. intelligence cited by an American judge over the summer. After multiple Free Joseon attempts to lure away North Korean diplomats, those living abroad were given a lecture at a meeting last summer in Pyongyang about loyalty to the regime, according to two people familiar with intelligence about the event.

The operations of Free Joseon and its founder, a Yale-educated former human-rights activist named Adrian Hong, have split North Korea watchers, who argue over whether he is a rogue meddler who risks doing more harm than good, or an admirable opponent of a harsh regime. Among other things, the group worked on plans for an alternative government if the Kim regime falls.

Free Joseon and Mr. Hong have gone mostly quiet since an ambitious operation in Spain last year went wrong. In a cascade of mishaps, including a diplomat’s wife injuring her leg as she tried to escape the embassy compound, members aborted the mission and made dramatic escapes to the U.S.

Organized resistance to the regime inside North Korea is almost unheard of. Its citizens are watched by layers of surveillance. Suspected dissenters are sent to concentration camps, often with their families. In the absence of any internal opposition, North Korean exiles and freelancers like Free Joseon have stepped in. “Joseon” is the name of an ancient Korean kingdom and is still used by North Korea to refer to itself. This is the fullest account yet of the group and its activities.

Mr. Hong, 36, and other members are in hiding to avoid arrest and extradition to Spain, where they face charges including hostage taking and robbery. One associate, a former Marine named Christopher Ahn, was captured by U.S. Marshals and is out on bail on the condition he doesn’t communicate with the group. He is fighting extradition.

A spokesman for Free Joseon said the group has provided valuable intelligence to foreign governments, including about North Korea’s nuclear program. It declined to comment on many specific matters related to its activities, including defections.

A U.S. official said Mr. Hong has helped hundreds of North Koreans defect, and added that Free Joseon isn’t funded or directed by the U.S. government.

Free Joseon’s roots date to the early 2000s, when Mr. Hong—a stocky, charismatic leader raised by Korean American missionary parents in Southern California—was a history major at Yale. Inspired by a memoir of a North Korean escapee who survived one of the country’s concentration camps, Mr. Hong helped found a nongovernmental organization called Liberty in North Korea, focused on helping North Koreans escape.

At the time, North Korean refugees were pouring over the country’s border with China seeking to escape famine and the country’s brutal police state. China sent captured refugees back to North Korea. Many were tortured or killed.

Mr. Hong said in public talks that he organized teams to develop safe houses for refugees in China so they could reach friendly embassies or countries open to helping them. The work was illegal under Chinese law. Mr. Hong said his group set up dozens of safe houses and aided hundreds of successful defections.

In 2006, Chinese authorities apprehended him and two associates, along with six North Koreans seeking asylum. Mr. Hong went on a hunger strike and tapped contacts, including U.S. lawmakers, to campaign for the group’s release.

After 10 days, Mr. Hong and his associates went free. Mr. Hong caught a glimpse of the North Koreans, still in detention, as he left.

“There is nothing like looking in the eyes of someone who thinks they are going to die,” he said at the time. At the urging of the U.S., China later released the North Koreans, too.

He eventually broke with Liberty in North Korea. Hannah Song, the group’s current president, said it no longer has any connection to him.

Mr. Hong began networking to form Free Joseon. Initially called Cheollima Civil Defense, it grew into a tightknit but compartmentalized operation involving scores of people, according to those familiar with the group. Its members helped identify high-ranking North Koreans who might be willing to defect and relied on encrypted communications. The group has sent out obscure codes to its members and North Korean rescuees on the internet like “Crocus 383765 459165 453666 486023 001000,” whose meanings can’t be deciphered.

Once clean-cut and often seen in a dark suit, Mr. Hong gained weight and took to wearing a beard and his long hair in a bun or ponytail. He used multiple phones, carried his electronics in a bag lined with a metallic fabric that blocks digital eavesdropping, and met contacts in corners of obscure hotel lobbies around the world, those people said.

Mr. Hong’s project became public in 2017 after the murder of Kim Jong Un’s half brother, Kim Jong Nam. U.S. officials have blamed the attack on North Korea, which it denies.

Messrs. Hong and Ahn, the former Marine, raced to Macau and escorted Kim Jong Nam’s family to Taiwan, where agents from a Western intelligence agency helped them travel to a third country.

A month after the killing of Kim Jong Nam, Cheollima Civil Defense introduced a website showing a short video of his son, Kim Han Sol, saying he was with his mother and sister. A new version was later posted in which he thanks Mr. Hong.

The video was interpreted by many North Korea experts as an effort to show Kim Jong Un that other family members, who could potentially head a new government someday, remained safe.

A message on the website said it could help other North Koreans escape and asked for bitcoin donations. An analysis of the digital wallet provided shows it received about $33,000.

Over the next year, the website boasted of two more rescues and encouraged others to ask for the group’s help.

When it came to extracting North Korea’s top diplomat in Italy in 2018, Mr. Hong couldn’t have asked for a better setup than the North Korean Embassy in Rome. The compound sits on a hilltop in a posh suburb where chauffeurs often wait in vehicles along the quiet streets, making it easy for a getaway driver to blend in.

Getting to Mr. Jo was the hard part. North Korean diplomats are rarely allowed to be alone in public, part of a Pyongyang policy to prevent people like Mr. Hong from luring them to defect or recruiting them into foreign intelligence.

Wherever Mr. Jo went around Rome, he was accompanied by an apparatchik called Mr. Pak. Though Mr. Jo introduced Mr. Pak as his aide, Italian politicians who met the two said they assumed they were paired up to spy on each other.

Several Italian lawmakers and activists said Mr. Jo, who dressed in dark suits and the “Supreme Leader” pin that North Koreans must wear, launched into a defense of the country at the slightest hint of criticism. His manners were so formal that Italian officials believed he’d undergone extensive etiquette training.

Still, after dining with local friends on his favorite fish dishes and hearty wines, Mr. Jo let others pick up his tab—common among cash-strapped North Korean diplomats.

“He was so intrinsically North Korean, we were all shocked” when he defected, said Osvaldo Napoli, an Italian lawmaker who heads a commission on cooperation with North Korea and met Mr. Jo multiple times.

Mr. Jo was living in Rome with his wife and a daughter, then 17 years old, a sign of trust given that some North Korean officials overseas must leave loved ones in Pyongyang as insurance against defection.

It’s unclear exactly how and when Mr. Hong and Mr. Jo met, but a person familiar with the matter said that Mr. Hong adopted the pretext of being a businessman interested in investing in North Korea.

Mr. Jo made his last appearance at a cocktail event to celebrate North Korea’s independence day in September 2018.

Italian politicians and economists milled about the embassy’s reception room.The walls were mostly bare, save the obligatory framed portraits of Kim Jong Un’s father and grandfather. The hosts served wine, “but only a tiny sip in the cup,” one guest recalled. At one point Mr. Jo delivered a strident anti-U.S. speech.

He also held forth about his impending return to Pyongyang, scheduled for the end of November. He said he was hoping to make one last trip in Italy, recalled Antonio Razzi, a former Italian senator who is active in North Korean issues and considers Mr. Jo a friend. Mr. Razzi made plans for a goodbye lunch in late November.

By then, Mr. Jo was gone.

After the Jos walked out of the embassy, the Free Joseon driver took the couple to a safe house, according to people familiar with their moves, and Mr. Hong arranged to deliver them to a Western government as political asylum seekers.

News of Mr. Jo’s defection leaked out thousands of miles away in South Korea, where intelligence sources learned of it through their own channels.

Then reports emerged that, in a heart-wrenching twist, Mr. Jo and his wife fled without their daughter, who North Korean officials have said suffers from an undisclosed psychological disorder. The girl had been left behind in the embassy and was sent back to Pyongyang.

That alarmed some Italian officials, given North Korea’s history of brutal punishments on families of suspected political dissidents.

After Italian officials publicly raised concerns about the matter, North Korea’s embassy sent a letter to Mr. Napoli, the Italian lawmaker who knew Mr. Jo. The letter said the defections were spurred by a “family quarrel” between Mr. Jo and his wife over how to care for their daughter’s condition. Following an intense dispute, the pair walked out of the embassy, intentionally leaving the girl behind. She then asked to return to Pyongyang to be with her grandparents, the letter said.

Mr. Jo was unreachable and Free Joseon declined to elaborate on the girl’s situation.

North Korea observers say it’s possible the Jos purposely left their daughter behind, given the history of defectors who have made a difficult decision to leave loved ones behind.

Other observers say they believe it’s more likely the girl was left behind as part of some mishap. Once defections are under way, they cannot be halted, given the risks the plot would be uncovered and everyone involved executed. In one possible scenario, some observers say, the family may have been trying to leave but for some reason their daughter was unwilling, forcing the parents to leave her.

Italy’s foreign ministry provided no further information other than to confirm the girl was sent back. North Korea’s embassy in Rome declined to comment.

The trouble surrounding Mr. Jo’s daughter triggered soul-searching within Free Joseon, according to people familiar with the group’s thinking. Her return to North Korea convinced Free Joseon it needed to do a better job of protecting defectors’ families.

For a potential extraction of a diplomat and his family in Madrid, the group came up with the idea of making it look like a kidnapping instead of a defection, those people said. That might just save the man’s family from vengeance by the Kim regime, the group reasoned.

The result was a much bigger and riskier operation than the Italian job. Entering the embassy disguised as kidnappers would amount to an invasion of North Korean territory.

On the team were Mr. Ahn; a Korean American film student; and a North Korean defector who lived in Los Angeles. Also in the group were at least five men in their 20s carrying South Korean passports, according to Spanish court documents.

Those documents and interviews with law-enforcement sources laid out a chain of events starting several months before the operation, when the group checked into a hotel near the embassy to scout out the site, a brown fortresslike building behind an ivy-covered wall.

In February 2019, Mr. Hong returned and approached the embassy, where he identified himself as Matthew Chao, a managing partner of a fictitious investment fund. Mr. Hong said he wanted to drop off a gift for an investor interested in doing business in North Korea and would like to speak to So Yun Suk, the commercial attaché—the man he’d eventually try to extract. Like Mr. Jo in Italy, Mr. So had become the embassy’s top diplomat in 2017 after a North Korean nuclear test led to the expulsion of the previous ambassador.

Mr. So came to the door, where the two men held a brief conversation. It’s unclear what they discussed.

Two weeks later, Mr. Hong returned, and approached the North Korean Embassy at about 5 p.m.

This time, members of Free Joseon were standing out of sight up the road. They had ski masks and fake pistols, plus knives, pipes, handcuffs, duct tape, a collapsible ladder and bags.

The person at the door recognized Mr. Hong, who was wearing a black suit and claimed to have an appointment with Mr. So. The man invited him inside the embassy wall to wait while staff searched for Mr. So.

Left alone, Mr. Hong opened the outer gate and signaled for his associates to rush in, according to investigators.

They acted with military efficiency, according to testimony from the seven embassy staff members inside. Brandishing fake guns, they bound the wrists of the North Koreans and placed bags over their heads.

A spokesman for Free Joseon said the men entered the embassy peacefully and they placed bags over the heads of the embassy staff for everyone’s safety, including Free Joseon’s.

Free Joseon members were speaking Korean with South Korean accents to the staff. Citizens of North Korea are indoctrinated from a young age to hate and fear the South. When they saw guns and heard South Korean accents, they concluded they were under attack from a ruthless enemy, according to their testimony.

One Free Joseon member, a defector from North Korea, stood on a chair and dashed framed portraits of Kim Jong Un’s father and grandfather to the ground. In North Korea, the portraits are revered as semi-sacred and it would be a crime punishable with death to desecrate them. A brief video released later by Free Joseon shows a man smashing the pictures.

By then, things were going awry. While the group subdued staff on the first floor, they missed one woman on the second floor—the wife of the man who had let Mr. Hong in the front gate.

Believing the embassy was under attack, she had hidden in her room and then climbed out on her terrace and jumped.

She hit her head, which began to bleed, and injured her leg. She limped through the embassy’s paddle tennis and volleyball court, exiting through a side entrance to the street. She hailed a passing motorist who drove her to a clinic down the road, where an ambulance was called.

Police officers arriving on the scene couldn’t understand what she was saying. Using Google Translate, they realized she was claiming intruders had invaded North Korea’s embassy nearby. She told them she thought they were South Korean spies.

More than an hour into the invasion, three Spanish police rang the doorbell, startling the Free Joseon group inside. Through the video intercom and sound of sirens, it was clear that police officers were at the door.

Mr. Hong, wearing a “Supreme Leader” lapel pin, headed to the door, where he pretended to be a North Korean diplomat. Greeting the police in Spanish, he assured them everything was fine. He also gently reminded them that under diplomatic codes, police must inform them officially if a North Korean citizen had been injured. The police decided not to push the issue at the door, but remained parked outside the embassy. Mr. Hong went back inside.

Free Joseon had isolated Mr. So, the senior North Korean diplomat, taken off his handcuffs and removed the bag over his head.

Members explained that their group was dedicated to human rights and urged Mr. So to defect, according to people familiar with Free Joseon’s account. His wife and son, who also lived in the embassy, were being held separately from the other staff members in a bedroom. If they left now, the family could plausibly say they were kidnapped, reducing consequences for his relatives back home, the Free Joseon members assured him.

Fearing his safety without a clear path to asylum, Mr. So refused, according to those people familiar. The fact that the police were lurking outside didn’t help.

He later told Spanish investigators the men tried to force him to defect against his will and become an “ambassador” of a new free Korean state that would take the place of the Democratic People’s Republic of Korea, or simply abandon his country for asylum in the West.

A video fragment reviewed by The Wall Street Journal shows Mr. So smiling and laughing briefly during a discussion with Mr. Hong. Free Joseon filmed much of the embassy invasion, but has released only a few snippets.

Mr. So and other embassy staff told investigators that they were severely beaten. Mr. So had bruises and a large wound on his face, according to a person familiar with the investigation.

Free Joseon denied beating anyone. The group said the wounds suffered by embassy staff were self-inflicted to avoid suspicion of complicity by North Korean investigators.

A person who answered the intercom at North Korea’s embassy in Madrid declined to comment. Mr. So couldn’t be reached for comment.

A lawyer for Mr. Hong, Lee Wolosky, said in a written statement that photographic evidence demonstrates Free Joseon members were invited into the embassy. He said embassy staff were later interviewed by Spanish authorities in the presence of more senior North Korean officials, making their accounts “inherently unreliable.”

Eventually Mr. Hong’s group gave up on trying to convince Mr. So. They bound him again and returned him to a conference room where other embassy staff were being held.

Free Joseon members ransacked offices looking for useful intelligence. They grabbed two pen drives, two laptops, a cellphone and a hard drive connected to an internal video camera.

More than four hours had passed since the invasion began. At least three police patrol cars were waiting outside. Any escape would have to be bold.

Mr. Hong’s group found the keys to three embassy vehicles, an Audi A8, a Mercedes Viano and a Toyota Rav4. They drove out the front gate and passed the waiting police who took them for North Korean diplomats, and got away.

Mr. Hong stayed behind to ensure no one tipped off police. Then he and one other group member slipped over a back wall, raced across a large vacant lot behind the embassy and called an Uber under the alias Oswaldo Trump.

The next day, Mr. Hong was in Lisbon catching a flight to New York.

Back in the U.S., according to court documents and people familiar with events, Mr. Hong scheduled a meeting with the Federal Bureau of Investigation, where he turned over the USB sticks and other material from the embassy, expecting agents to view him as an informant working in the national interest.

It was a crucial misjudgment. The FBI decided it was too risky to engage with a group carrying out such operations on foreign soil. The agents divulged Mr. Hong’s identity to Spanish authorities investigating the embassy break-in, and eventually sent the computer hardware Mr. Hong had delivered back to Spain.

The FBI declined to comment.

Using that information, footage from security cameras and testimony from embassy staff, Spanish authorities pieced together the events and figured out the names of other Free Joseon team members. Spanish authorities have charged Mr. Hong and four others with a range of crimes including breaking and entering, assault, hostage taking, theft and forgery.

In April, U.S. Marshals broke down the door in a Los Angeles apartment used by Mr. Hong.

He had already gone underground. The FBI had earlier informed Free Joseon that it had received credible intelligence of a threat involving North Korean assassins against the life of Mr. Hong and other group members.

Inside the apartment was Mr. Ahn, who was immediately arrested. He was released on bail in July, while his lawyers prepare for the extradition trial. His lawyers declined to comment.

The others remain at large. A wanted poster published in April 2019 for Mr. Hong said he was last seen driving a white 2017 KIA Soul with license plate “ARDENT.”

He hasn’t been seen since.

--Giovanni Legorano and Ethan Millman contributed to this article.

Write to Bradley Hope at bradley.hope@wsj.com, John Lyons at john.lyons@wsj.com and Alastair Gale at alastair.gale@wsj.com

Corrections & Amplifications U.S. Marshals raided the home of Adrian Hong in April 2019. An earlier version of this article incorrectly stated it happened in May 2019. (April 3, 2020)