A court in Moscow has convicted a Russian police officer on charges of spying for the United States and sentenced him to 15 years in prison.

The Moscow City Court on Thursday found Roman Ushakov guilty of treason by handing over classified information to the U.S. The prosecutors produced his messages containing sensitive information about the Interior Ministry, and a cache disguised as a rock containing cash and a letter from the CIA, according to the Interfax news agency.

The conviction is the latest in a host of spy cases amid Russia-West tensions over Ukraine.

Interfax quoted prosecutor Viktor Antipov saying Ushakov has been caught red-handed, pleaded guilty and gave detailed testimony about his contacts with the U.S. Antipov said Ushakov worked in Siberia, but gave no further details.