A few days before Christmas, a convoy of security vehicles invaded a quiet corner of Weilheim, a quaint Bavarian town of pastel squares and fastidiously kept cobblestone streets. The target seemed as unassuming as the setting: a local children’s soccer coach.
Nothing ever stood out about the man, fellow coaches recalled. He was not short, but not tall — friendly, yet never wanting to discuss anything but soccer. Grasping for words, most landed on the same choice: “unremarkable.”
That changed when they learned he had been arrested on charges of treason and spying for Russia in one of the gravest espionage scandals in recent German history.
The coach, a 52-year-old former German soldier, worked for Germany’s Federal Intelligence Service, or B.N.D., as a director of technical reconnaissance — the unit responsible for cybersecurity and surveilling electronic communications. It contributes about half of the spy agency’s daily intelligence volume.
As a Russian mole, he would have had access to critical information gathered since Moscow invaded Ukraine last year. He may have obtained high-level surveillance, not only from German spies, but also from Western partners, like the C.I.A.
German intelligence has had a long and troubled history of Russian infiltration, stretching back decades. But the latest case now threatens to shake the sometimes tentative trust of Western intelligence agencies in Germany at a critical moment when Russia’s invasion of Ukraine has presented Europe with its biggest security threat since World War II — and as Moscow is escalating its espionage efforts across the continent.
The arrest came shortly after a flurry of raids across Europe that uncovered so-called illegals, or secret Russian agents, in the Netherlands, Sweden and Norway.
The German authorities are still trying to determine what damage their mole may have done. But the discovery of a double agent has sent a chill through German political circles.
Some leaders are openly questioning the loyalties of their own security services, and just how deep the problem of Russian sympathizers runs within their ranks.
The case has already led to a second arrest — that of a Russia-born accomplice, who acted as a courier, and, according to one official, brought some 400,000 euros in cash to Mr. Linke from Moscow for his information. It is still not clear who recruited whom, two people following the investigation said, but the authorities believe the men were put in touch by a German military reservist who is a member of the far-right populist party, the Alternative for Germany, or AfD.
The Germany authorities — who, in public, hailed the arrest as a victory against Russia — have batted away journalists’ inquiries. They have identified their chief suspect, the soccer coach, only as Carsten L., in keeping with strict privacy laws. British news outlets have identified him as Carsten Linke. A New York Times investigation confirmed his name, hometown and background.
Privately, three officials familiar with the investigation — who requested anonymity in order to share details because discussing the inquiry publicly is illegal — worry the case could be the tip of an ominous iceberg.
“Recruiting other spies is the top tier of espionage,” one of the officials said. “And our technical reconnaissance unit is one of the most important departments of the B.N.D. To find someone relatively high up there? That makes this case explosive.”
German intelligence was apparently tipped off to the mole by a fellow Western agency, those following the investigation said.
The case has also exposed other serious vulnerabilities — about Germany’s lack of vigilance over Russian espionage and its unpreparedness to mount counterintelligence operations — which allies like Washington and London had long warned about.
For years, as German politicians pushed economic ties with Moscow — in particular, buying its gas — they closed down many intelligence units focused on Russia.
Yet President Vladimir V. Putin of Russia, who started his career as a K.G.B. agent in Communist East Germany, took the opposite tack: He made Germany, Europe’s biggest economy, a priority target.
“They have highly specialized experts who speak fluent German, who know their way around very well, and who launch very targeted operations in Germany,” said Nico Lange, a former German Defense Ministry official, who is now a senior fellow at the Munich Security Conference. “On our side, you actually have almost no one left who knows Russia, speaks fluent Russian, and watches the other side closely.”
Investigations so far suggest that Mr. Linke’s connection to Moscow predated the invasion of Ukraine last February. The question plaguing German officials, should the accusations be confirmed, is what would drive an intelligence officer, a nationalist who spent years in the military serving his country, to then turn against it?
No clear financial incentives have been found, nor was Mr. Linke in debt.
The only hints of potential motives are his apparent far-right sympathies. A search of his home and offices, two people familiar with the investigation said, found fliers from the far-right AfD party. At work, Mr. Linke had openly told colleagues he felt the country was deteriorating, and he was particularly disdainful of its new center-left government, one of those following the inquiry said.
Over the years, far-right groups have grown increasingly sympathetic to Russia, enamored of Mr. Putin’s nationalistic rhetoric. Germany has struggled to root out far-right sympathizers in its security services, including in the military, even dismantling part of its special forces.
Mr. Linke’s digital footprint, under aliases discovered by German media, was small.
A Google account of his, using the alias “Steen von Ottendorf,” first found by Germany’s Der Spiegel newsmagazine, has one YouTube subscription: a channel that collects nationalist tunes. The channel’s icon bears an eagle — and the red, white and black of Germany’s old imperial colors, often used by the far right.
Ottendorf is a town in eastern Germany with no clear connection to Mr. Linke, but it is home to a thriving “Reichsbürger” scene. The Reichsbürger, a loosely aligned far-right group, believe in a conspiracy that the modern German state does not actually exist. Some of the group’s followers were behind a coup plot that German police foiled late last year.
One German politician following the investigation worries that some military and intelligence officials still admire Russia and aspire to closer relations, even after the invasion of Ukraine.
“It’s a kind of conviction, wanting to cooperate with Russia — it’s a romantic belief,” the official said. “I worry there are many others who hold that conviction in our security services.”
To Germany’s allies, such concerns may seem familiar. Since the days of the Cold War, Germany’s intelligence agency suffered from Russian infiltration, said Erich Schmidt-Eenboom, a historian who has written several books on the agency and keeps a list of all of the B.N.D. agents who were “turned,” exposing hundreds of operatives.
Among them was the 1961 case of Heinz Felfe, a K.G.B. mole who revealed B.N.D. operations across Europe. After the fall of the Soviet Union, Germany learned that a top director, Gabriele Gast, who worked closely with the chancellery, spied for the Stasi, the East German secret police, for 17 years.
“The B.N.D. has been considered by all partner services to be a complete molehill,” Mr. Schmidt-Eenboom said. “Its internal security has failed over the years — time and time and time again.”
According to Mr. Schmidt-Eenboom, the information available to Mr. Linke was vast: internet espionage, German surveillance stations, mobile listening devices in southern Ukraine, and the German Navy’s reconnaissance ships observing the war from the Baltic Sea.
On top of that, Mr. Linke would have had access to reports from allied American services like the C.I.A. and the National Security Agency, as well as from Britain’s Government Communications Headquarters.
Mr. Linke appeared to use that to his advantage, having requested reports related to Russia or the war from an employee who herself was investigated, but then later released as an unwitting accomplice, according to the people who have been following the investigation.
Shortly before Mr. Linke was discovered as a mole, he had been promoted to head personnel security checks. The damage he might have done there would have been far greater: He could have passed on tips about agents vulnerable to blackmail or bribes.
Some officials informed on the investigation say German intelligence has played down the what confidential information may have made it into Russian hands, saying only that German intelligence was confirmed as having been sent to Moscow.
But Western security officials worry that Mr. Linke also passed along intelligence on the Ukraine war from allies — in particular, possibly the British.
Two German policymakers worried that Western partners would become less willing to share intelligence.
“I’m deeply concerned that our allies will feel worried that they cannot trust us, that we’re leaky like a sieve,” said one of the officials, who spoke on the condition of anonymity to discuss the case.
A month after Mr. Linke was taken into custody, an accomplice, Arthur Eller, 31, was detained by the F.B.I. in Miami. After an interrogation, he was put on a plane to Munich, where he was arrested by German investigators.
A naturalized citizen, Mr. Eller was born in Russia and moved to Germany with his parents in the 1990s. He also served in the German armed forces.
Mr. Eller worked more recently as a businessman with ties to companies in Germany and Africa, including a Nigerian-registered petroleum trading company he ran alongside a Swiss-based gold dealer and a Nigerian businessman.
He and Mr. Linke are believed to have first met in 2021, three people familiar with the investigation said, at a yearly festival run by the Weilheim sports club where soccer coaches and their families snacked on coffee and cake or drank beers in the afternoon. The two were put in touch by one of Weilheim’s local AfD members, who once served in the military with Mr. Eller and remains a reservist.
Travel logs and flight records found by a Russian investigative group, the Dossier Center, show Mr. Eller took hundreds of flights to New York; Los Angeles; Dubai, United Arab Emirates; Baku, Azerbaijan; Belgrade, Serbia; Tbilisi, Georgia; Prague; Doha, Qatar; Shanghai; Geneva; and countless Russian cities.
Many trips to his native country were very short, but he usually stayed in the best hotels in Moscow and St. Petersburg, according to the Dossier Center. He also made trips to surprisingly obscure Russian locations, like Nizhnekamsk.
Mr. Eller has been cooperating with the investigators, people familiar with the operation said. Mr. Linke has so far remained silent.
According to people following the inquiry, Mr. Eller has told investigators that he believed that he was working with Mr. Linke on a B.N.D. operation. But German authorities have expressed wariness of his version of events.
Mr. Eller also said he served as a courier, taking documents to Russia and bringing money back. Four times, he said, he passed envelopes of cash late last year to Mr. Linke, one person familiar with the investigation said.
At their last handoff, Mr. Linke’s boldness apparently went as far as to have a B.N.D. agent working at the Munich airport pick up Mr. Eller and collect a final cash exchange for him — an envelope that investigators believe held 100,000 euros.
The German authorities are investigating that person but have not labeled the agent a suspect. Rather, so far, they believe that the agent was an unwitting accomplice.
Yet for some German officials, that is hardly a reason for relief.
“Every time we dig,” one said, “it just gets deeper and deeper.”
Julian E. Barnes contributed reporting from Washington, and Oleg Matsnev from Berlin.