Suspicions about a British embassy security guard accused of spying for Russia were aroused after he stopped withdrawing money from his bank account, it was claimed last night.
Police and MI5 became interested in David Smith, 57, after they noticed he had not used debit or credit cards for some time, according to the German magazine Spiegel.
The authorities in Berlin suspected he had an alternative source of cash, which they now believe were funds from the Russian intelligence services handed over in exchange for secrets about his job at the British embassy in the city.
This information he is said to have provided was believed to have been “low-grade” and included material such as lists of visitors to the embassy, according to the magazine’s sources in German intelligence.
On at least one occasion it included references to staff at the German foreign ministry.
Mr Smith, known as Smudge, was arrested on Tuesday at his home in Potsdam, a 30-minute drive from the German capital where he worked.
It is understood he was employed locally by the embassy where he had worked for three or four years.
It emerged that the former RAF serviceman was firearms trained and had worked as a member of the Germany Guard Service (GGS), a civilian force often made up of ex-Servicemen who are employed to protect military bases.
Erich Schmidt-Eenboom, the author of books about German intelligence, said Mr Smith’s work for the GGS could be of interest to investigators.
“Was he a watchman, or something more senior? We simply don’t know,” he said.
Soviet memorabilia was in plain sight at the home Mr Smith had once shared with his wife, who is believed to be from Odessa, Ukraine, before she moved out.
Among other items in his home were letters sent from the Dnipropetrovsk province of the Ukraine, and a biography of Reinhard Heydrich, the high-ranking Nazi.
Senior politicians have questioned the quality of vetting procedures given the abundance of evidence pointing towards potential sympathy for Russia.
On Friday night, shopkeepers near his home described Mr Smith as a “gentleman” who spoke fluent German, liked coffee, pastries and buying flowers and potted plants.
Verkark Khayah, who works at the Backerei Exen, recognised Mr Smith from a photograph obtained by The Telegraph showing the moment of his arrest on Tuesday.
“He would come in for coffee every now and and again,” he said. “He would often sit outside and eat a croissant at about eight in the morning. He spoke German really well.”
The alleged spy was also identified at a nearby florist.
Yvonne Weigand, whose mother runs Emmy florists, said he showed a preference for potted house plants with lots of greenery.
“I dealt with him a couple of times because I’m the one who speaks to the English-speaking customers, but he would speak German to me as well,” she said.
Whitehall officials believe Mr Smith offered the Russians a list of persons entering and exiting the embassy.
However, because British agents normally use aliases when signing in to embassies the information is thought to have been low risk.