FBI AGENTS REVEAL HOW RUSSIAN OPERATIVES LIVED IN THE UNITED STATES AS AMERICANS AND TRIED TO GATHER GOVERNMENT SECRETS IN "THE FBI DECLASSIFIED: THE SPIES NEXT DOOR"

Alana De La Garza, Star of CBS' "FBI" Drama Series, Narrates

Tuesday, Oct. 13, 10:00 PM

FBI agents take viewers inside one of the Bureau's most important counterintelligence investigations to track Russian operatives living in America and seeking critical secrets, in the next edition of CBS News' THE FBI DECLASSIFIED: "The Spies Next Door," to be broadcast Tuesday, Oct. 13 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

Narrated by Alana De La Garza from CBS' drama series FBI, "The Spies Next Door" reveals the dangerous hunt to find and stop the spies in a wide-ranging FBI investigation called "Operation Ghost Stories." Agents bugged the spies' homes, followed their travels and ultimately cracked their secret communications network.

"Operation Ghost Stories was probably the largest FBI counterintelligence investigation in history," says Alan Kohler, assistant director of the FBI's Counterintelligence Division.

How did this happen?

By 2000, FBI agents learned there were multiple sets of Russian spies in the United States, posing as Americans.

Many were trained in Russia to assimilate into everyday American life by getting married, obtaining jobs and raising families, while also sending encoded messages back home, the FBI agents say. The spies lived double lives.

"They went to school with Americans. They went to July 4 parties with their neighbors," says Kohler. "And never once did anybody suspect they would be Russian spies."

Counterintelligence agents say the Russian spies got jobs they believed would allow them access to people in powerful positions. Their mission was to gather sensitive information that would be sent back to Moscow and potentially used to damage national security.

Every move they made was monitored.

"I did spend so much time watching them and listening to them and observing their actions. And a lot of ways I feel like I knew them better than I know some members of my own family," says FBI Special Agent Maria Ricci, about a couple of spies she observed in New Jersey.

FBI agents recorded several exchanges where the Russians passed large amounts of cash to each other in public places - to help finance their operations - and one instance where more than $60,000 was buried at a highway rest stop, to be retrieved later.

Could the FBI stop the spies before sensitive secrets got into the hands of the Russian government?

"You're always wondering, what are you missing?" says Ricci. "Do they have contacts? Do they have access to classified information? ... The risks... were astronomical."

THE FBI DECLASSIFIED features FBI agents and analysts taking viewers behind the scenes of some of the biggest cases they've solved during their careers. Through never-before-seen footage and in-depth interviews, each episode will focus on a different investigation and showcase the cooperation between the FBI and other law enforcement agencies.

THE FBI DECLASSIFIED: The Spies Next Door" is from the award-winning team behind CBS News' 48 HOURS. Anthony Batson is the executive producer. Matthew DeVoe is the director. Ruth Chenetz is the senior producer. Alicia Tejada is the senior coordinating producer. Resa Matthews and Anthony Venditti are the producers. Marcus Balsam and Phil Tangel are the supervising producer-editors. Libby Fabricatore and Maria Barrow are the editors. Pat Milton is the supervising development producer. Josh Gaynor is the development producer.

Follow CBS News on Twitter, Facebook and Instagram, and listen to podcasts at CBS Audio.