Sergei V. Skripal, the former Russian spy poisoned in Britain with a powerful nerve agent, appears to have been working in recent years with intelligence officers in Spain, a country locked in a pitched battle with Russian organized crime groups, some with ties to the Russian government.
The account of Mr. Skripal’s activities in Spain, provided by a senior Spanish official and an author who tracks the Spanish security apparatus, adds new details to a case that has inflamed relations between Russia and the West.
Rather than merely living an isolated life in retirement, Mr. Skripal, a former Russian military intelligence officer, continued to provide briefings to spies in the Czech Republic and Estonia, according to European officials. Now, it appears he was also active in Spain.
The revelation adds another striking parallel between Mr. Skripal and another former Russian intelligence operative, Alexander Litvinenko, who died in London in 2006 after being poisoned by a radioactive isotope, polonium 210. The Spanish authorities have acknowledged enlisting Mr. Litvinenko in a campaign against Russian organized crime figures in Spain.
Mr. Skripal has a long history in Spain. As a colonel in Russia’s military intelligence agency, widely known as the G.R.U., he was posted in Madrid in the mid-1990s, working undercover as a military attaché at the Russian embassy.
It was there, according to Russian court records, that he was recruited as a spy by the British intelligence service. That set off a chain of global events: his arrest in Russia in 2004, his release in a spy exchange with the United States in 2010 and his resettlement in England that same year.
But in recent years, Mr. Skripal returned to Spain for several meetings with officers from its intelligence service, CNI, though the content and precise timing of those meetings are classified, according to the senior Spanish official and the Spanish author, Fernando Rueda.
“He continued coming to Spain,” said Mr. Rueda, citing conversations with Spanish intelligence officers.
Then last March, Mr. Skripal and his daughter Yulia were poisoned with a rare and deadly strain of nerve agent, known as Novichok, at their home in Britain. It nearly killed them both.
Britain has accused Russia of poisoning Mr. Skripal, and on Wednesday it announced the first charges in the case, singling out two G.R.U. intelligence officers. In making their case, British investigators released security camera images tracking the two Russians to the scene of the crime, and then back to Moscow.
On Thursday, the leaders of the United States, France, Germany and others released a statement expressing “full confidence” in Britain’s assessment that the attack on Mr. Skripal had been carried out by the two officers. Speaking at the United Nations Security Council, Britain’s ambassador, Karen Pierce, raised the possibility of additional sanctions on Russia, which has vociferously denied any involvement in the poisoning.
The findings of the British investigation, particularly the involvement of two G.R.U. officers, suggest that the poisoning was carried out as an act of retribution by Mr. Skripal’s former colleagues.
But retribution for what, exactly?
Six months after the poisoning, a clear picture of the motive remains elusive. Was it a purely symbolic attack, a warning to other Russian operatives to remain loyal? Or did Mr. Skripal do something specific to anger his former comrades?
In the years after his resettlement in England, Mr. Skripal lived openly in his adopted city of Salisbury, drinking at the local pubs and grilling sausages in his yard.
But he traveled to Prague in 2012, where he spent a boozy lunch with Czech intelligence officers. And he went to the Estonian capital, Tallinn, in 2016 to brief local spies. On each of the trips, which were organized and approved by the British foreign intelligence service, MI6, he shared insights into Russian spycraft and possibly contributed information that led to the expulsion of undercover operatives.
“It contributed to improving our work,” said a European official with knowledge of the meetings.
Still, Spain is a special case.
Since the fall of the Soviet Union, Spain has been a haven for Russian crime bosses and corrupt officials fond of Lamborghinis and sprawling villas on the Costa del Sol. Some are believed to have ties to the Kremlin.
Mr. Skripal’s continued visits to Spain were confirmed by a current senior official, who would not provide additional details. But former officials said that Mr. Skripal would have been especially useful in crackdowns on Russian organized crime.
“From the beginning we had a big problem,” said a retired Spanish police chief, who spoke on condition of anonymity to discuss confidential investigations. “We ignored the Russian phenomenon and its organized crime. We didn’t know how they operated.”
“Skripal, Litvinenko,” he said, “they gave a more accurate idea of the reality.”
Spanish prosecutors and police investigators have acknowledged working with Mr. Litvinenko, an expert in Russian organized crime who fled to England after publicly falling out with Vladimir V. Putin when he was director of the Federal Security Service.
At the British inquest into Mr. Litvinenko’s death, his family’s lawyer claimed that he was also a paid agent of the Spanish intelligence agency and had planned to travel to Spain to hand over evidence about possible links between the Kremlin and Russian organized crime figures. He was killed before he could make the trip.
Officials would not say whether Mr. Skripal was involved in similar work, or, as in Estonia and the Czech Republic, was simply giving lectures to Spanish spies. Such visits would not have been illegal, nor are they uncommon for former spies trying to remain useful.
Mr. Skripal’s Russian colleagues, though, might have viewed things differently.
Aleksandr Gusak, a retired Federal Security Service colonel, has spent a lot of time thinking about traitors. He was Mr. Litvinenko’s superior officer at the time he defected to Britain. Russians, he said, had a kind of genetic antipathy toward traitors, though he added that if he had carried out the attack on Mr. Skripal he would have used “a sword rather than a spray.”
“I was raised on Soviet ideas,” Mr. Gusak said. “For me, a traitor, you spit on them, grab them and shoot them. Or hang them and piss on their grave.”