The former head of Germany’s top foreign intelligence agency was arrested on Tuesday on suspicion of attempted treason and espionage, suspected of selling state secrets to foreign powers.

August Hanning, 80, who was the head of Germany’s equivalent to the CIA, the Federal Intelligence Service, from 1998 to 2005, was arrested along with a former aide, identified as Manfred D. Germany’s federal prosecutor’s office said Hanning was “strongly suspected of treasonous espionage, spying out state secrets, attempted treason, and espionage.” The two are accused of giving classified information to a foreign intelligence service over the course of several years, though the identity of the foreign intelligence service wasn’t revealed.