Ten people accused of espionage for Russia in a case that has gripped America have pleaded guilty in New York to spying for a foreign country.
Money-laundering charges were dropped. Correspondents suggest the guilty plea may facilitate a Cold War-style prisoner exchange.
The judge ordered the immediate deportation of the 10.
The mother of suspect Anna Chapman has said she expects her to fly home to Russia on Friday.
US and Russian officials have not confirmed or denied that assertion.
The 10 pleaded guilty to "conspiracy to act as an unregistered agent of a foreign country".
It was the first time they had all appeared in public together since being arrested last month.
An 11th suspect went missing after being released on bail in Cyprus, where he had been staying.
Prosecutors said the accused had posed as ordinary citizens, some living together as couples for years, and were ordered by Russia's External Intelligence Service (SVR) to infiltrate policymaking circles and collect information.
Suggestions of a prisoner swap emerged in Russia, where the family of a man jailed by Russia for espionage told the BBC he had had to confess in order to be included.
Igor Sutyagin was transferred from a prison near the Arctic Circle to a Moscow jail.
He told his family in Moscow he would be flown to Vienna on Thursday and released as part of a deal between the US and Russian governments.
Earlier, Sutyagin's lawyer was quoted by Russian media as saying he had arrived in the Austrian capital, but his father Vyacheslav denied the reports.
"This is all speculation, don't take it seriously," he told the BBC.
Austrian officials have neither confirmed nor denied the reports.
News of Igor Sutyagin's release was broken by his lawyer in Moscow, Anna Stavitskaya, who quoted the prisoner's father.
She said Vyacheslav Sutyagin had been informed by a journalist's phone call that his son had arrived at a Vienna airport and been met "by an officer".
Ms Stavitskaya said she had not been able to confirm the news with the Russian authorities. Sutyagin was jailed in Russia in 2004 for spying for the CIA.
His brother Dmitry said Igor had been told by Russian officials that his release would be part of a spy swap, and that US officials had been present at a meeting.
Dmitry added that his brother had seen a list of about 10 Russian prisoners that the US had given Moscow that included Sergei Skripal.
Skripal is a Russian military intelligence (GRU) officer convicted of spying for the UK in 2006.
Russian newspaper Kommersant said the list included Alexander Zaporozhsky, a former employee of Russia's Foreign Intelligence who was jailed for 18 years for espionage in 2003, and Alexander Sypachev, sentenced in 2002 to eight years in jail for spying for the CIA.
In a move that fuelled speculation about a swap, a top US diplomat met the Russian ambassador to Washington on Wednesday.
No details were given of the talks between Under-Secretary of State for political affairs William Burns, a former US ambassador to Moscow, and Ambassador Sergei Kislyak, other than the fact that the issue of spies came up in the meeting, in which they also discussed Iran.