Those released by Russia:
Alexander Zaporozhsky, a former colonel in the Russian foreign intelligence service, sentenced in 2003 to 18 years in prison for espionage on behalf of the US. Zaporozhsky quit the service in 1997 and settled in the US; Russia enticed him back and arrested him in 2001. He was convicted on charges of passing secret information about Russian agents working under cover in the US and about American sources working for Russian intelligence. A US global intelligence company, Stratfor, said that Zaporozhsky was rumoured to have passed information leading to the capture of Robert Hanssen and Aldrich Ames, both extremely valuable double agents in the US intelligence services.
Sergei Skripal, a former colonel in the Russian military intelligence, was found guilty of passing state secrets to Britain and sentenced to 13 years in prison in 2006. He was accused of revealing the names of several dozen Russian agents working in Europe.
Igor Sutyagin, a military analyst with the USA and Canada Institute, a respected Moscow-based thinktank, was sentenced to 15 years in 2004 on charges of passing information on nuclear submarines and other weapons to a British company that Russia claimed was a CIA cover. Sutyagin has insisted on his innocence, saying the information he provided was available from open sources.
Gennady Vasilenko, a former KGB officer employed as a security officer by Russia's NTV television was arrested in 2005. In 2006 he was sentenced to three years in prison on murky charges of illegal weapons possession and resistance to authorities. Reasons for his involvement in the swap weren't immediately clear.
Russian agents released by America
Anna Chapman, 28, is the daughter of a Russian diplomat. She is the most recognisable of the agents after her former husband sold photographs to the press showcasing her social life and travels. Her attorney, Robert Baum, said she had visited the US on and off since 2005 before settling there. Previously, she had lived for seven years in the UK after marrying an Englishman. Chapman is her married name; she's now divorced. Her maiden name is Kushchenko. Prosecutors say Chapman used a specially configured laptop computer to transmit messages to another computer of an unnamed Russian official.
She was arrested at a New York police department precinct after turning in a fake passport an undercover FBI agent had given to her. She pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Tracey Foley, 47, lived in Cambridge, Massachusetts, and is married to Donald Howard Heathfield. The couple has two sons, Tim Foley, 20, a student in Washington, DC, and Alex Foley, 16. Foley was an estate agent who showed houses in the Boston area. She worked on a contract basis for the firm Redfin.
She pleaded guilty to conspiring to act as an unregistered agent of a foreign country. Her real name is Elena Vavilova.
Donald Heathfield, 49, lived in Cambridge, Massachusetts, and is married to Tracey Lee Ann Foley. He graduated from Harvard's John F Kennedy School of Government with a masters in public administration in 2000.
Heathfield worked as a sales consultant at Global Partners Inc, a Cambridge-based international management consulting firm. He also had his own consulting company, Future Map Strategic Advisory Services LLC. Prosecutors said Heathfield met in 2004 with an employee of the US government to discuss nuclear weapons research. He pleaded guilty to conspiring to act as an unregistered agent of a foreign country. His real name is Andrey Bezrukov.
Juan Lazaro, 66, told people for decades that he was born in Uruguay and was a Peruvian citizen, but he is actually Russian and his real name is Mikhail Vasemkov. He studied at the New School for Social Research, now called The New School, a university in Manhattan. He taught a class on Latin American and Caribbean politics at Baruch College, also in Manhattan, for a short time in 2008.
An agent for Russia for years, Lazaro brought his wife, Vicky Pelaez, into the conspiracy by having her pass letters to the Russian intelligence service on his behalf. The couple's home in Yonkers, New York, was also paid for by Russian intelligence. He pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Vicky Pelaez, 55, married to Juan Lazaro, was born in Peru. She worked in New York City as a columnist for one of the United States' best-known Spanish-language newspapers, El Diario La Prensa. She had come to the US after being briefly kidnapped by a leftist guerrilla group in Peru in 1984.
Pelaez lived under her real name and was an American citizen, but now plans to return to Peru after a brief stay in Russia, according to her attorney.
The couple have a teenage son. Pelaez also has a 38-year-old son from a previous marriage.
She pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Richard Murphy, with his wife, Cynthia, are the parents of two daughters, Kate, 11, and Lisa, 9. The family, who lived in a suburban neighbourhood in Montclair, New Jersey, had been in the US since the 1990s.
Neighbours say Richard, 43, mostly stayed home with the children, caring for them and the home, while his wife had a well-paid job in New York City. Born Vladimir Guryev, he pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Cynthia Murphy, married to Richard Murphy, lived in a suburban neighbourhood in Montclair with their daughters, Kate, 11, and Lisa, 9. Concealing her true name Lydia Guryev, the 39-year-old worked for Morea Financial Services, a lower Manhattan-based accounting firm that offered tax advice, earning $135,000 a year, and had recently earned her MBA.
Prosecutors said one of her assignments had been to network with Columbia University students.
She pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Mikhail Semenko of Arlington, Virginia, worked at the Travel All Russia travel agency in Arlington leading up to his arrest. Semenko attended Amur State University on Russia's border with China, where he was enrolled in a Chinese studies programme. It was there he met Slava Shirokov, owner of the travel agency that eventually employed Semenko. After arriving in the US, he received a graduate degree from Seton Hall University in New Jersey. Shirokov said Semenko liked to attend functions at the Russian embassy and talked about landing a job in international relations. He pleaded guilty to conspiring to act as an unregistered agent of a foreign country. Semenko is his real name.
Patricia Mills, 36, is the assumed name for Natalia Pereverzeva, living in the US with Mikhail Kutzik (see below), who used the name Michael Zottoli. Like Kutzik, she held a bachelor's degree in business administration from the University of Washington, obtained in 2006.
Neighbours describe the two as a smiling, attractive couple raising a young son and toddler in an Arlington, Virgina, high-rise apartment.
They moved to northern Virginia last year from Seattle. Prosecutors have said they are making arrangements to send the children home to Russia. She pleaded guilty to conspiring to act as an unregistered agent of a foreign country.
Michael Zottoli, 41, is the assumed name for Mikhail Kutzik, who was living as part of a married couple with Natalia Pereverzeva, purporting to be Patricia Mills. In Seattle, he worked at Premier Global Services, Inc, a telecommunications firm, from 2007 to 2009. Zottoli earned a bachelor's degree in business administration from the University of Washington in 2006. He and Mills moved to northern Virginia last year. After his arrest, he and his purported wife admitted that Zottoli and Mills were assumed names and provided their real names, which had not been known at the time of their arrest. He pleaded guilty to conspiring to act as an unregistered agent of a foreign country. The couple have two young children.
And the one who got away
Christopher Metsos is the suspected paymaster for the US spy ring. He was arrested on 29 June in Cyprus on an Interpol warrant as he tried to board a flight for Budapest, Hungary. Released on $33,000 (£21,000) bail a day later, he promptly disappeared and is now a fugitive. Canadian authorities said he was travelling as a 54-year-old tourist on a Canadian passport that stole the identity of a boy who died at five years of age. He has been charged with conspiring to act as a foreign agent and conspiracy to commit money laundering. Authorities have not released any other identity for him.
