The family of retired U.S. Marine Paul Whelan said “his innocence is undoubted” in a statement published on Tuesday, even as Whelan was held in a Russian jail on charges of espionage.

Whelan, a 48-year-old Michigan resident who currently works in corporate security. According to his family, he was in Moscow to attend a wedding when he was arrested on Friday. Russia’s FSB security service did not acknowledge the arrest until Monday when it claimed Whelan was detained on a “spy mission.” As of Wednesday, the FSB has not clarified the charges or produced any evidence against Whelan.

The family statement was posted on Twitter by Paul’s brother David:

We have read reports of the arrest in Moscow of Paul Whelan, our son & brother. Paul is a retired Marine and was visiting Moscow to attend a wedding. We noticed that he was not in communication the 28th, which was very much out of character for him even when he was traveling. We learned of his arrest on Monday morning after his detention was picked up on newswires and have contacted Congressional representatives, the U.S. Embassy, and the State Department. We are deeply concerned for his safety and well-being. His innocence is undoubted and we trust that his rights will be respected.

David clarified in an MSNBC interview that his brother was part of the wedding party and was asked by the groom to lead tours around Moscow and the Kremlin because he had visited Russia before. He told USA Today the groom is a friend who served with Paul in the Marines.

“He loves to travel so I wasn’t at all surprised that he would be confident going to Russia. He has a law enforcement background, he’s got his Marine background, he does corporate security and he’s aware of the risks of traveling in certain parts of the world,” David said of Paul.

“It just never would have occurred to me that A) he would have any sort of trouble in a large metropolitan area or B) that his background would suggest that he would be willing to commit any crime, let alone an espionage crime,” David said.

“I can’t imagine how someone with a law enforcement background who is also a former US Marine, and who is now working in corporate security and is also aware of the risks of travel, would have broken any law let alone the law related to espionage,” David told BBC News on Tuesday.

USA Today reported on Wednesday that Paul Whelan’s military records show him serving in the Marine reserves from 1994 to 2008, with deployments to Iraq as an administrative clerk in 2004 and 2006. The records say he was discharged in 2008 after he was convicted “on several charges related to larceny.”

The Detroit Free Press elaborated that Whelan was “convicted at a special court-martial in January 2008 on several charges related to larceny and was given a bad-conduct discharge in December 2008 at the rank of private.”

The Free Press said Whelan was a police officer between 1988 and 2000, then worked at the Kelly Services consulting and temporary service agency from 2001 to 2016, taking jobs that included “campus security as well as electronic and IT-related security.”

Whelan’s current employer BorgWarner, an auto parts supply company, also released a statement on his arrest, saying, “We can confirm that Mr. Whelan currently serves as the company’s director, global security. He is responsible for overseeing security at our facilities in Auburn Hills, Michigan and at other company locations around the world.”

Confirmation of Whelan’s arrest led to speculation he was taken hostage in retaliation for actions by the U.S. government, possibly including sanctions or the prosecution of Maria Butina as an agent of the Kremlin. The arrest was compared to China’s sudden interest in collecting Canadians after Canada’s arrest of Huawei executive Meng Wanzhou, which is ironic given that Whelan was also born in Canada.

Global financier Bill Browder, a devoted critic of Russian President Vladimir Putin, gave an interview to the Detroit Free Press on Wednesday in which he bluntly accused Putin of taking Whelan hostage because Maria Butina made a deal with prosecutors:

“I think Putin is in a raw panic because of Maria Butina, the Russian woman who was caught trying to basically take money from Russia and contribute it to the Trump campaign via the NRA,” Browder said. “She has pleaded guilty and offered to cooperate with Robert Mueller’s investigation. Up until five days ago, there was 100 percent chance she was going to cooperate. Now, all of a sudden, Putin has taken a hostage, an ex-military officer. This gives him some possibility of negotiating a prisoner swap.” Butina pleaded guilty in December to conspiring on behalf of the Kremlin to cultivate sources inside the Republican party prior to the 2016 presidential election. Until Dec. 28, when Paul Whelan, a retired Marine from Novi, was taken into custody, without the knowledge of embassy officials or notification of his family, “the Russians had no leverage,” Browder said. “All of a sudden, they have an American hostage and everything changes in terms of their position. Make no mistake, this is a hostage situation.”

Browder argued that people accused of espionage under circumstances like Whelan’s are normally deported, not arrested and threatened with 20 years in prison. Other analysts noted that Russia rarely arrests Americans for espionage and low-level intelligence work is usually carried out by people with some diplomatic cover.

Former CIA operative John Sipher told NPR Whelan is “absolutely not” the kind of operative American intelligence services would recruit for a mission to Russia, because “we would never put a U.S. citizen, without diplomatic immunity, in harm’s way this way, especially looking after low-level things like this.”

Sipher largely agreed with Browder’s notion that Butina’s arrest is “more severe than we think it is” and the Russians grabbed Whelan because “they think getting Ms. Butina out is pretty important.”

The Russian Foreign Ministry said U.S. consular officials were allowed to visit Whelan on Wednesday afternoon. Earlier on Wednesday, Secretary of State Mike Pompeo said the United States will “demand his immediate return” if his detention is “not appropriate.”