In early August, Pablo Gonzalez was taken from a prison in Poland and flown to Moscow on a plane carrying Russian secret agents, hackers and an assassin from Russia's Federal Security Service (FSB).
The group was welcomed at the airport by a military guard, a red carpet and the President of Russia, Vladimir Putin, who thanked them for their loyal service to the country.
In the video that night in Moscow, Gonzalez can be seen smiling while shaking hands with Putin in front of the plane.
With a black beard and shaved head, Gonzales wore a T-shirt from the movie series Star Wars on which it was written: "Your empire needs you".
The 42-year-old, known to his Russian friends as "Pablo the Basque journalist," was among a group of Russian prisoners in the West who exchanged for citizens of Western countries and Russian dissidents in early August.
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The group freed by Vladimir Putin included two opposition activists who accused Gonzalez of spying on them.
He was arrested in Poland in 2022 for alleged espionage.
"I started to have doubts in 2019, it just dawned on me," Žana Njemcova tells me in the first interview she gave about Gonzales spying on her.
The two met in 2016 at an event related to the investigation into her father's murder.
Boris Nemtsov, a fierce opponent of Vladimir Putin, was killed a year earlier near the Kremlin.
His daughter - herself a vocal critic of Putin - eventually moved to Europe for security reasons.
That day in Strasbourg, Pablo González asked Nemcova for an interview with a local newspaper in the Basque Country, an autonomous community of Spain.
She initially refused to talk.
But the journalist, a Spaniard of Russian origin, gradually inserted himself into her circle of people - he attended events, recorded conversations, appeared in places where she was.
Recalling the sequence of events, Nemtsova says that she became cautious.
"I shared my doubts with several people, but they told me: 'Oh no, that's nonsense!'
"People think you're crazy if you say things like that. They may also think you're paranoid.
"But I was absolutely right."
That's why she decided to speak openly now.
"I want other people to be very careful," explains Žana Njemcova.
"The threat is not something you only read in books or watch in the cinema. It's very close."
Gonzalez was formally charged with espionage only a week after he left Poland and flew to Moscow as part of a major prisoner exchange in early August.
Until then, he had been in prison for more than two years awaiting trial.
All the while, Polish prosecutors refused to talk about the case and the proceedings, and the intelligence remains secret.
The Polish lawyer who first represented Gonzalez says he cannot comment on the case.
Watch the video: Welcome of exchanged prisoners - finally at home
At the time of his arrest, Gonzales had lived in Warsaw for at least three years, most of that time with his Polish girlfriend.
He was a freelance journalist and worked mostly for Spanish-language newspapers.
He reported on the war between Armenia and Azerbaijan in Nagorno-Karabakh and traveled to Ukraine.
With a group of journalists, he also went on a trip to Syria organized by the Russian Ministry of Defense, which always carefully chooses who it takes.
He was briefly detained in Ukraine in 2022, although the Security Service of Ukraine (SBU) did not disclose the details.
On February 28, Gonzalez was arrested in Przemyśl, in eastern Poland, where he was part of a group of journalists covering the beginning of the Russian invasion of Ukraine.
The reason for the arrest was not disclosed.
Last year, evidence of Gonzalez's activities was presented to Zhana Nemtsova as part of the investigation.
"I have no doubt that he was a spy. I'm sure, 100 percent," she told me.
Njemcova is barred under a non-disclosure agreement from disclosing details of the evidence.
Because of this, she had to listen to people declaring that Gonzalez was innocent.
"It's scary. The importance of this should not be minimized.
"These people have no moral scruples. They consider you enemies," she warns, referring to Russian intelligence.
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Although Nemcova says she never trusted Gonzalez as a true friend, he managed to insert himself into her social circle.
She says that he has been supplying information about her group from the very beginning.
"He can be very charming, he knows how to communicate with people, to put them at ease."
Her ex-husband Pavel Elizarov agrees with that.
He and Gonzales were "pretty close for a while."
He would visit him in Spain, they would talk about politics and go sightseeing.
He met others with his friend.
Ilya Yashin, another prominent activist, went with Gonzalez to a soccer match in Spain and they even went shopping together for a coat.
When Gonzales was released in a prisoner exchange, Yashin was also part of the deal: he was imprisoned in Russia for condemning the war in Ukraine.
Vadim Prokhorov, the lawyer of the Nemtsov family, points to another detail.
"He drank like a Russian," Prokhorov told me.
"He could drink without getting drunk. We should have suspected him even then!".
We requested an interview with Gonzales through his wife, who lives in Spain and is his biggest supporter.
So far, he has not responded.
But he appeared on a show on Kremlin-controlled television, in which he wanders the Moscow suburbs, recalling in perfect Russian how he sledded on cardboard as a child.
He was born, he explains, as Pavel Rubtsov, a name that still appears on his Russian passport.
He became Pablo Gonzalez in 1991 when he moved to Spain with his mother.
During the Spanish Civil War, his grandfather was evacuated to the USSR, so Pavel and his mother were entitled to Spanish citizenship.
All of this made him the perfect man to be recruited by Russian intelligence, but a state television report said Poland had no evidence of this.
"They threatened me and put pressure on me," Gonzalez says in his extremely deep voice.
"I asked: 'What did I do?', and they said: 'You know.' But I didn't know."
No one I interviewed described Gonzalez as a Putin admirer, although Zhana Nemtsova says the two were on "different sides of the political spectrum."
"I didn't sense any pro-Russian hint in him," said a source in Poland.
But on Russian television, Gonzales was quite excited as he described meeting "Vladimir Vladimirovich Putin" at Vnukovo Airport in Moscow.
He said that he "practiced" the greeting with his president the whole way.
"I wanted to make sure I gave him a strong, manly handshake," says Gonzales, with a big smile.
The BBC did not have direct access to any material in this case.
But we have interviewed reliable sources whose statements, when taken together, reveal that Pablo Gonzalez was supplying information about a large number of people in Europe.
When he was taken into custody, Polish investigators uncovered reports detailing the movements, contacts and profiles of people over a period of several years.
One of the targets was Russian opposition activists, including people close to Zhana Nemtsova.
There is a report of at least one Polish citizen, as well as students of a summer journalism school run by Njemcova.
Investigators also found emails that Gonzalez had copied from a laptop loaned to him.
We don't know who these reports were sent to, but they list the costs of gathering information, as well as travel costs.
"There were many details, including what they had for lunch," the BBC was told.
In some cases, the source said, questions were added, and it was obvious that the superior was asking for clarification or more details.
One of the reports refers to a visit to Syria by a group of journalists, including Gonzalez, organized by the Russian Ministry of Defense, although the report mainly contains criticism of the Ministry for the poor organization of the trip.
According to the official indictment, Gonzalez is charged with espionage - providing intelligence, disseminating disinformation and "conducting operational reconnaissance" for Russia's GRU military intelligence service.
We do not know if and what other evidence exists, but it is not known how significant the material he collected about the Russian opposition is.
I have been told that some reports are "sloppy" and contain data downloaded from the Internet.
"Some were quite wordy, on 10 pages instead of one. Probably for the sake of obtaining additional funds", the source believes.
The part about sloppiness fits the description of a close friend of Gonzalez who told me that he is "a bit lazy".
The BBC has learned that the accuracy of the reports deteriorated significantly after 2018, as notes or corrections by a senior officer or manager are seen.
It may be a coincidence, but at that time a large number of Russian intelligence officers were expelled from Europe, after the double agent Sergei Skripal and his daughter were poisoned in the British city of Salisbury.
Although Russian activists who were friends with "Pablo the Basque journalist" were shocked to learn that he had betrayed them, they do not believe that he had access to classified information.
"We are not in the habit of sharing such information with anyone, because we have always known that we can have such problems," says Žana Nemcova.
"Everything we told him, we would have told anyone else publicly," opposition politician Vladimir Kara-Murza told me after being released in the same prisoner exchange.
One source tried to downplay the case against Gonzalez, describing the contents of the report as "frivolous."
But Nemtsova, whose father was killed in Moscow because of his political views, does not agree with that.
"His words were important to the GRU (Russian military intelligence). Maybe they led to serious consequences.
"This does not mean that Pablo personally did something. But they have other people doing it.
"That's why this is serious."
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When Gonzalez was taken into custody, a series of protests followed, accusing journalists of espionage.
The European Union has expressed deep concern about the rule of law under the previous Polish government, while groups such as Reporters Without Borders have called for Gonzalez to either be allowed to defend himself in court or be released.
"I thought maybe they made a mistake arresting him," says a Polish journalist who knew Gonzalez.
"I thought it was just to show that the government was doing something about Russia."
Since Gonzalez was never convicted, his most ardent supporters still claim that Poland "got away" with the injustice it inflicted on him.
But most of them were silenced by last month's prisoner exchange and a festive welcome in Moscow.
From the beginning, the government in Madrid did not say much about this case.
"But that exchange of prisoners and the welcome of Gonzalez answers all the questions," the Spanish official told me.
It would be very strange if Vladimir Putin, known, as she says, as a man who stifles media freedom, "rescues" an ordinary journalist.
Weeks after Gonzalez arrived in Moscow, the spy scandal continues to cause headaches for Nemtsova.
During 2018 and 2019, the foundation she founded after her father's murder invited "Pablo, the Basque journalist" to Prague to give a lecture on war reporting.
The summer school for young journalists was hosted by Charles University in Prague.
After the Czech media reported that the academic community had been "infiltrated", a doctoral student wrote a scathing letter to the university's Faculty of Arts, warning that the Nemcov Foundation could pose a security threat to "the entire Czech Republic".
Student Aleksandar Paršankon proposed to suspend master's studies in the Russian language supported by the Nemtsov Foundation until the end of the investigation.
He told the BBC that these studies "by definition are attractive to Putin" and asked that students of this program be warned that "their safety cannot be guaranteed".
Njemcova calls the claims of this student "unfounded and manipulative", and the student himself says that there is no real evidence.
But the foundation is part of Zhana Nemtsov's father's legacy, and she fears that the goal is to "kick us out of college."
"I am a victim of espionage," she says.
"It can happen to people like me, but that doesn't mean we are a threat to the Czech Republic."
Pablo Gonzalez was returned to Moscow by Russia, where he was identified on the basis of his passport as Pavel Rubtsov.
Spain does not strip people of their citizenship, even those suspected of espionage.
But Gonzalez will have to renew his Spanish passport at some point.
While a case of espionage has been opened in the European Union, the chances of him visiting Spain are quite slim, and it is not known how long it may take.
As for visiting his sons in Spain, the official in Madrid was clear: "They can visit him in Moscow."
When an intelligence officer is exposed, his options are limited in terms of continuing his work and freedom of movement.
Other Russians who have engaged in similar work generally end up as stars of state-controlled TV stations.
Maybe Pablo will change his name to Pavel and start praising Vladimir Putin a lot more.
As for Zhana Nemcova, she admits that she is now even more careful about who she hangs out with.
"I always think about safety now," she told me.
"Earlier, I was thinking about my safety, because I left Russia. But I didn't think about security in Europe.
"Now, of course, I'm thinking about it. And I'm very careful."
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