Every couple of years, David Heathfield and his family pull out photo albums and recall the brief life of his brother Donald, who died in his crib near Montreal in 1962. It wasn't until Monday that they discovered, during those intermittent and short episodes of grief, an alleged Russian spy had been using his dead brother's name to infiltrate the corridors of power in the United States.

When U.S. prosecutors released an indictment Monday that alleged a covert cell of men and women from Russia's SVR intelligence agency had adopted the identities of average American residents, it came as a shock to the alleged spies' unsuspecting co-workers and neighbours. But for the Heathfield family, one question looms large: how did an undercover Russian "illegal" come to steal their dead baby brother's identity?

"It's weird. It's interesting. How would they get that information? Where would it come from?" said David Heathfield from his home in Brampton, Ont., just north of Toronto.

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The real Donald Heathfield was the third of four children born to Shirley and Howard Heathfield, a restaurateur who passed away in 2005 from cancer. The Federal Bureau of Investigation believes that a Russian spy - identified officially in court documents as "Defendant #4" - assumed the dead infant's identity around 1999 and settled in the Boston area. During the next decade, the spy - who was married to another alleged spy and purported Canadian citizen - ingratiated himself with a former legislative counsel to the U.S. Congress, as well as a high-ranking bureaucrat with knowledge of nuclear weapon development, court records allege.

David Heathfield speculated that the SVR must have learned of his brother's death through an old newspaper death notice. According to the U.S. investigators, the alleged secret agent had an authentic looking birth certificate that lists the names of the real Donald's parents. However, the middle name on the certificate, Howard, is a fabrication, David Heathfield said. His brother's middle name was Michael.

Baby Donald's family was never in the sort of circles that would put them in the vicinity of covert operatives, David Heathfield said. After leaving Montreal, his father ran The Ruffage, a restaurant in a suburban mall in Burlington, Ont. His parents' vacations were usually to sunny locales such as Las Vegas and Bahamas, he said. "They weren't world travellers, believe me."

Asked what he would say to the alleged spy who tried to pass off his baby brother's identity as his own, Mr. Heathfield replied: "You picked a good name. Heathfield's a great name - but don't deface it."

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Defendant # 5, aka Tracey Lee Ann Foley

The supposed wife of the man accused of using Donald Heathfield's identity, this woman's alleged cover story was that she was a native of Canada who became a naturalized citizen of the United States. According to court records, a small notation on a strip of film helped to reveal her true background. When the FBI raided a safety deposit box belonging to Ms. Foley, they discovered the strip of negatives - all pictures of the woman in her 20s. On all the slides, the name of the company that produced the film had been excised, except for one slide. The company was called Tacma, a Russian film processor.

Defendant #1, aka Christopher R. Metsos

The man who goes by the name of Mr. Metsos is the only alleged spy not to be detained, and is still at large. According to the charges, he resides outside the United States, purports to be a Canadian and serves as a money courier for the alleged cell. FBI agents observed him providing bags, believed to contain cash, to the alleged spies, and once buried cash in the ground that was later retrieved by another operative.

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Defendant #7, aka Patricia Mills

One half of a couple that got their start in Seattle in 2003, the woman claiming to be Ms. Mills drove her husband - another alleged spy - to the site where Mr. Metsos was accused of burying cash. FBI agents also allegedly intercepted conversations where the accused were whining about the sufficiency of her Canadian identification cards, complaining that they hindered her ability to travel.