The ex-spook, identified as the 43-year-old Anton Robert K., was posted to Pristina in 2005 to set up a network of informants on behalf of the BND. Among them was a Macedonian man who grew up in Germany, Murat A. Approved by the BND security checks, the 29-year-old was hired as an interpreter and translator.
But the two became romantically involved and moved in together and K. began sharing state secrets and offering access to classified documents between 2007 and 2008, prosecutors said.
Der Spiegel news magazine reported that K. divulged the secrets "in the bedroom" or by allowing his lover to access to his computer.
But K. neglected to reveal their personal relationship to his superiors.
According to media reports, the BND only learned of the relationship when K.'s wife, who still lived in Germany with their children, informed them that he had changed his life insurance policy, making A. the beneficiary.
After the BND informed prosecutors, the two were called back to Germany in March 2008 and arrested.
On Wednesday, the higher regional Munich court found K. guilty of 21 fraud charges and sharing state secrets, sentencing him to two years and three months in jail.
His boyfriend A. received a suspended sentence of one year and two months for “reconnoitring state secrets,” which prosecutors alleged the Macedonian had given to other organised crime contacts, though they were unable to prove this during the trial.
The couple were also charged with claiming fraudulent expenses of €14,700.
The defence claimed the couple were victim to a homophobic witch-hunt within the BND, which was embarrassed by the affair, not least because it gave the interpreter clearance.
The organisation has also reportedly been forced to sever contacts with more than a dozen informants in the Balkans due to the scandal.