The government identified the man as Alexey Karetnikov and said that he had been ordered removed from the United States by an immigration judge.
Federal law enforcement officials say Karetnikov entered the United States last October.
Karetnikov admitted that he was present in the United States in violation of immigration law and voluntarily agreed to deportation in lieu of further court proceedings, deputy Homeland Security press secretary Matt Chandler said in a statement.
Once deported, Karetnikov would face criminal and civil penalties if he returned without U.S. government permission, Chandler said.
Law enforcement officials said the man had been staying in a different part of the United States from the Russian agents who were arrested on criminal charges June 27 and had no ties to them other than that his name came up as part of the same criminal investigation.
The Justice Department investigated thoroughly and would have prosecuted Karetnikov if authorities had had enough evidence to do so, the officials said.
To date, investigators have uncovered no evidence the man possessed, retained or passed on sensitive or classified information, said one of the officials.
The officials spoke on condition of anonymity earlier Tuesday in order to discuss details that went beyond court documents. The matter was first reported by The Wall Street Journal.
In the biggest spy swap since the Cold War, 10 Russian agents who infiltrated suburban America were deported last week in exchange for four people convicted of betraying Moscow to the West. They were all living near New York, Washington or Boston. An 11th defendant, the ring's alleged paymaster, has been a fugitive since fleeing authorities in Cyprus after his release on bail.
On Tuesday, the brother of Igor Sutyagin, who is one of the four freed by Russia, told APTN that Igor is staying at a hotel near London. His brother Dmitry said Igor's only complaints are mild stress and fatigue, he has stopped seeing a psychologist because he is in good mental condition, and he is not ready to face the news media.
Igor Sutyagin has met with British officials, who assured him a British visa is ready and that he should receive it by Wednesday, his brother Dmitry told APTN. Igor Sutyagin told officials who asked him whether he would like to work that he is undecided about his future, Dmitry Sutyagin added.
Igor Sutyagin, an arms control researcher, was jailed in Russia in 2004 on charges of passing information to the CIA.