A shadowy group committed to ousting North Korea's leader Kim Jong-un has claimed it was behind a raid last month at the North Korean embassy in Spain.
Cheollima Civil Defense, a self-styled human rights group, reportedly fled with computers, a phone and hard discs.
The break-in occurred just days before a key summit between US President Donald Trump and North Korean leader Kim Jong-un in Hanoi, Vietnam.
The group denied using force, saying it was "not an attack".
However, a Spanish high court judge said the 10 assailants shackled, beat and interrogated embassy staff in the incident on 22 February.
It remains unclear why the raid took place. Cheollima wrote online that it had "responded to an urgent situation in the Madrid embassy".
It said it had "shared information of enormous potential value" with the FBI, the US intelligence agency, "under mutually agreed terms of confidentiality".
What happened in the raid?
On Tuesday Judge José de la Mata lifted a secret decree on the investigation, according to a document from Spain's High Court.
The break-in began at 16:34 (15:34 GMT), it said, and most of the intruders fled at 21:40.
The judge said the group had "identified themselves as members of a human rights movement seeking to liberate North Korea".
One of their number, named as Adrian Hong Chang, allegedly gained access to the embassy by asking to see the commercial attaché, whom he claimed to have met previously to discuss business matters. His accomplices burst in once he was inside, the judge said.
The group are accused of interrogating the attaché and trying to persuade him to defect. When he refused, they left him tied up in the basement, the judge said.
Two other members of the break-in group were named as US citizen Sam Ryu, and a South Korean, Woo Ran Lee.
The judge said that embassy staff were held hostage for several hours.
One woman managed to flee, escaping through a window and screaming for help. Concerned neighbours quickly called the police.
When officers arrived, they were greeted by Adrian Hong Chang, posing as a North Korean diplomat in a jacket with a Kim Jong-un lapel badge.
He told the police that all was well, and nothing had happened.
That evening most of the group fled the embassy in three North Korean diplomatic vehicles, the judge said. Mr Hong Chang and some others left later via the back entrance using another vehicle.
They split up into four groups and headed to Portugal, the court document said.
Mr Hong Chang - a Mexican citizen who lives in the US - allegedly contacted the FBI to give his version of events five days later.
What do we know about this group?
Cheollima Civil Defense (CDC), also known as Free Joseon, is committed to overthrowing North Korea's ruling Kim dynasty.
CDC first came to prominence after taking credit for getting Kim Jong-un's nephew, Kim Han-sol, safely out of Macau after the assassination of his father.
Kim Jong-nam - who was the North Korean leader's estranged half-brother - was murdered at an airport in Malaysia in 2017.
Kim Han-sol has expressed his desire to go back to North Korea, and has referred to his uncle as a "dictator".
'Exposed from the shadows'
Analysis by Laura Bicker, BBC News, Seoul
The Cheollima Civil Defense has been a topic of conversation among journalists for months. Now, courtesy of Spanish High Court papers, we have the names of some of those suspected of being behind the raid on the North Korean embassy in Madrid. But there are still so many questions.
Adrian Hong Chang was the leader, according to the Spanish High Court. Mr Hong Chang is a well-known North Korean human rights activist. He has helped defectors flee North Korea in the past. But where would he get the funding and the know-how to carry out an operation such as this?
Mr Hong Chang is also said to have handed over all the documents and computers taken from the embassy to the FBI. Just days later, reports started to appear in the US media giving more details about the raid, including sources linking the incident to the Cheollima Civil Defense. The group claims in its statement that this was a "betrayal of trust". The intelligence it gathered has certainly not saved its members from potential prosecution, and they are now at risk of possible North Korean reprisals.
Mr Hong Chang is undoubtedly a wanted man. Not only by the Spanish High Court, but most probably by Pyongyang. This operation has exposed a group which was once in the shadows and put it firmly in a legal spotlight where it may not want to be.
What have authorities said about who is behind it?
Sources close to the investigation reportedly told Spanish newspaper El País that the operation was planned perfectly, as if by a "military cell".
And the attackers seemed to know what they were looking for. Spanish authorities suspect US intelligence agencies and their allies could have been involved in the attack, according to daily papers El País and El Confidencial.
Victims of the alleged assault have reportedly told investigators the men spoke in Korean.
El País even reports that two of the group have links to the US Central Intelligence Agency (CIA). The CIA declined to comment to the BBC.
Asked if there was any US government involvement in the raid, State Department spokesman Robert Palladino told a regular news conference on Tuesday: "The United States government had nothing to do with this."
Why would anyone attack the embassy?
Reports say the attackers could have been looking for information on North Korea's former ambassador to Madrid, Kim Hyok-chol, who was expelled from Spain in September 2017 over North Korea's nuclear testing programme.
Mr Kim is now serving as a key envoy in North Korean talks with the US, and helped organise the summit in Vietnam. He also travelled to Washington DC with Kim Jong-un's right-hand man, Kim Yong-chol, in January.