An advocate for an imprisoned Russian scientist, Igor V. Sutyagin, said on Thursday that he had evidently been released in return for the Russian suspect Anna Chapman, in a prisoner exchange redolent of the Cold War.

The advocate, Ernst Chyorny, said Mr. Sutyagin – who has served 10 years of a 14-year sentence for espionage — had called his father from Vienna, where he was met by a British officer. Family members who met with Mr. Sutyagin this week in Moscow said he had been informed he would be transported through Vienna to Britain, where he would be freed. Mr. Sutyagin’s mother, a chemical engineer in a scientific community outside Moscow, rushed home from work when she heard the news.

“So far I don’t know what happened,” said the mother, Svetlana Y. Sutyagina. “I am in a state of suspense.”

The reported exchange was not confirmed by Russian or American officials on Thursday, though anticipation had built throughout the day.

The scientist’s lawyer, Anna Stavitskaya, said Mr. Sutyagin had verbally agreed to an exchange during a meeting with Russian officials who he believed were from Russia’s Foreign Intelligence Service, or S.V.R., and that Americans had also been present at the meeting.

Her comments followed reports from Washington on Wednesday that just days after the F.B.I.’s sensational dismantling of a Russian spy ring, the American and Russian authorities were negotiating an exchange of some or all of the 10 espionage suspects for prisoners held in Russia, including Mr. Sutyagin.

Ms. Stavitskaya said Mr. Sutyagin had consistently denied spying for the United States, for which he was sentenced to a 14-year term, but this week he signed a document admitting guilt.

“If he is free, the United States could be thanked for one thing, for saving a person,” she said. “I am thankful to the United States, if it was the United States that included him on the list. If at last he is freed — not in the way we wanted, because we wanted him to restore his good name, but it is difficult to do it, given our judicial system — at least he will be freed in this way,” she said. “If he leaves today, it will happen quietly.”

A spokesman for Russia’s Foreign Intelligence Service would not comment on the case on Thursday. American officials in Washington confirmed that talks had taken place on Wednesday, but made little further comment.

(Read More: NY Times)