The man worked as an intelligence officer for the Office for the Protection of the Constitution, the BfV, and had converted to Islam.
“The BfV has managed to expose a suspected Islamist among its associates,” the agency said in a statement.
The 51-year-old German national was arrested for sharing “sensitive information” online – understood to be coda for leaking intelligence secrets to other Jihadists. He is suspected of links to Isis but this remains unconfirmed.
A BfV spokeswoman he had “made Islamist remarks online under a false name, and had offered internal information during online chats”. The man is now in detention and his mobile devices and computers being analysed to gauge the extent of his treachery.
The man, a former bank clerk, had been at the agency for several months starting in April of this year. His brief was to monitor the Cologne Islamist scene.
Included in the logs of his chats were messages in which he talked to fellow radical Islamists while attempting to recruit them into the spy agency to help plan attacks against “non believers.”
According to German media reports not even the suspect”s wife knew that he had covertly converted to Islam.
His conversion was allegedly made via a phone call in which he pledged an oath to a Salafist Imam named Mohamed Mahmoud who previously preached in Berlin before moving to Syria to fight for Islamic state.
The BfV noted that he was “inconspicuous” during his application and all through his training. The agency did note the man’s attention to secrecy as they discovered multiple storage devices detailing internal operations, assignments and deployments.
The spy was finally caught after trying to recruit who he thought was a fellow Islamist into the agency on the internet who was actually a fellow agent at the BfV.
Prosecutors are drawing up charges for a case of “preparing a serious act threatening state security”.