(CNN) -- An American lawyer based in Moscow who used to work at the U.S. Embassy there was expelled from Russia two weeks ago, his law firm said on Monday.
Thomas Firestone was refused admission to Russia on May 5, according to the law firm Baker & McKenzie.
"We have no reason to believe that our colleague has engaged in wrongdoing of any kind," the firm said in a statement. "Neither our colleague nor we have been informed of the reason for this action."
Until 2012, Firestone was the resident legal adviser at the U.S. Embassy in Moscow, specializing in crime and corruption issues in Russia. In September, he became a senior counsel in Baker & McKenzie's Moscow office. Now he is working at the firm's Washington office, the firm said.
The U.S. State Department was not notified of the expulsion, a spokesman said Monday, and Russia would not be obliged to inform the United States. "I don't have any information on this particular individual," said spokesman Patrick Ventrell. "He was a private citizen."
According to the New York Times, one source familiar with the case said Firestone turned down a March request from Russian intelligence operatives to spy for Russia. It is unclear whether that alleged approach is related to his expulsion. But after a trip abroad, when Firestone tried to return to Russia, he was detained for 16 hours at the Moscow airport and was eventually put on a plane to the United States, the newspaper said.
A representative at the Russian Embassy in Washington declined to comment, and according to Russian state news agency RIA Novosti, Russia's Foreign Ministry declined to comment as well.
A week after Firestone's expulsion, Moscow publicly announced the expulsion of another American, Ryan Fogle, who worked at the U.S. Embassy. Fogle was accused of trying to recruit Russians to spy for the United States, and Russian officials released a video of him being detained while wearing a wig. The video also showed a map, a compass and other paraphernalia that were said to be in his possession at the time.
Top officials from Russia and the United States have denied that the espionage claims are affecting relations between the two countries.
But at least one former counterintelligence official says the expulsions are designed to send a message.
"These things are stage-managed; they're orchestrated for maximum effect," said Joel Brenner, who served as the national counterintelligence executive from 2006 to 2009 and wrote the book "America the Vulnerable." "The Russians are letting us know across the board now that they're not our friends."