U.S. authorities have taken a 12th Russian national into custody in connection with the spy ring that led to the exchange of 10 others last week. A U.S. official said the 23-year-old Russian citizen was detained on immigration charges. The man, who was not identified, has not been charged and is in the process of being deported, the official said. A law official said the individual’s name came up in the course of the FBI’s investigation into the Russian illegal agents, but investigators were not able to gather enough evidence to bring criminal charges against the man. Federal authorities handling the case came to the conclusion that his case was different from that of the 11 people charged with being Russian agents last month. Ten of the spy suspects in federal custody entered plea deals on Thursday as part of a diplomatic agreement to swap them for four people held by Russia, most on charges of spying for Western intelligence agencies. The swap took place at the airport in Vienna on Friday.