WASHINGTON (AP) — Secretary of State Mike Pompeo said the U.S. hopes to soon get access to Paul N. Whelan, the former Marine detained in Russia on espionage charges.

Pompeo said Wednesday at a news conference in Brazil that the U.S. has “made clear to the Russians our expectation that we will learn more about the charges and come to understand what it is he’s been accused of.”

Paul Whelan was arrested in Moscow on Friday. The Russian Federal Security Service announced the arrest three days later and said Whelan was caught “during an espionage operation,” but it gave no details.

The Michigan resident’s service record was released Wednesday by the Marine Corps at the Pentagon and shows he was court martialed and given a bad-conduct discharge.

He joined the Marine Reserves in 1994 and rose to the rank of staff sergeant in 2004. Whelan was an administrative clerk and administrative chief and deployed for the war against Iraq for several months in 2004 and 2006. He was convicted at a special court martial in January 2008 and given the bad-conduct discharge in December 2008 at the rank of private. Details of the larceny charges were not released.

Whelan’s last place of duty was Marine Corps Air Station Miramar in California.

His brother, David Whelan, said Whelan was in Moscow to attend a wedding and that his “innocence is undoubted and we trust that his rights will be respected.” He said the family is “deeply concerned for his safety and well-being.”

Pompeo said that “if the detention is not appropriate we will demand his immediate return.”

The Russian spying charges carry a prison sentence of up to 20 years.