German authorities said Thursday that they have arrested a second person in connection with a high-profile espionage case that embarrassed Germany's foreign intelligence agency.

Federal prosecutors said Arthur E., whose surname wasn't released for privacy reasons, was detained at Munich airport last month after arriving from the United States.

Prosecutors said the suspect, a German citizen, is accused of treason for passing secrets obtained by Carsten L., an acquaintance working at Germany's BND spy agency, to Russian intelligence.

STABBING ON GERMAN TRAIN KILLS 2, INJURES 7; MOTIVE REMAINS UNKNOWN

German BND logo

The entrance to the headquarters of Germany's Federal Intelligence Service is shown above. German authorities arrested a man in connection with an espionage case that embarrassed the country's BND spy agency. (Christophe Gateau/picture alliance via Getty Images)

Arthur E. was not an employee of the BND, prosecutors said.

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German authorities received support in their investigation from the FBI, they said.