Vladimir Veitman, a former specialist for Estonian counterintelligence, has been found guilty of spying for Russian secret services.
Officials on Wednesday also revealed the name of his recruiter and said Veitman had warned Russian services that Estonian authorities were on to another agent.
In a closed courtroom, Veitman was sentenced to 15 years in prison for treason and other charges in a plea bargain.
Having retired from the Estonian counterintelligence and anti-corruption agency KaPo (often referred to in English as the Internal Security Service) in 2011, Veitman was arrested last August over suspicions that he had provided classified Estonian intelligence to Russia's secret services over the years. He pled guilty and was said to be cooperative with investigators.
At a press conference, prosecutors and KaPo representatives revealed that Veitman was recruited by Nikolai Ermakov, a Russian citizen who was born in Tallinn in 1948, for the Russian intelligence agency SVR. Yermakov, who was in Estonia in the summer and is currently in St. Petersburg, has an Estonian residence permit that expires next July. The two had worked together in the same unit when Veitman was a KGB employee.
Yermakov's boss was allegedly Valeri Zentsov, who was mentioned in the Estonian annual security report in 2009 in connection with Herman Simm, another Estonian enlisted by Russian intelligence services. Veitman met with Ermakov three or four times, mainly in Estonia except once in Croatia in 2007, where Zentsov was also present.
In one example of the damage caused, it was revealed that Veitman notified Russian officials that Estonian authorities were on to Simm.
But unlike Simm, Veitman did not have access to NATO and EU secrets.
The head of the Internal Security Service, Arnold Sinisalu, attributed Veitman's motive to personal issues, such as discontent with his career, and later the incentive was mainly financial. Money was also the primary incentive of the two other Estonians who have been convicted for spying, Sinisalu pointed out.
Authorities confiscated 120,000 euros, including 89,000 euros in cash that was discovered in various hideouts. But Veitman kept his spending conservative, knowing that officials of his line of work are watched.
Two other Estonians have previously been convicted of spying - former senior defense official Herman Simm, who was sentenced to 12 years in 2009; and former security official Aleksei Dressen, sentenced last year to 16 years in prison.
Dressen's wife, Viktoria Dressen, was also found guilty of treason, but did not receive real jail time.