MIAMI — A psychology professor and his wife pleaded guilty yesterday to reduced federal charges in a case involving allegations that both had spied for the Cuban government for decades.Carlos Alvarez, 61, pleaded guilty to conspiracy to become an unregistered foreign agent. His 56-year-old wife, Elsa Alvarez, admitted knowing about her husband’s illegal activities but failing to report them to authorities.

Carlos Alvarez faces up to five years in prison and his wife up to three years on the revised charges. Both were charged previously with the more serious charge of acting as illegal Cuban agents, which carries a longer possible prison sentence.

US District Judge K. Michael Moore set sentencing for February 27.

Carlos Alvarez, a professor at Florida International University, was accused of spying for decades on Cuban-American exile groups and prominent individuals in Miami, as well as reporting on US political affairs. His wife, also a university employee, was implicated to a lesser degree in the alleged spying.

The couple’s arrests in January followed years of FBI surveillance, which included placing a listening device in the bedroom of their Miami home and wiretaps on their telephone. The FBI said Carlos Alvarez, known to the Cubans by the code name “David,” used a short-wave radio and encryption techniques to communicate with his Cuban handlers.

Carlos Alvarez’s lawyer, Steve Chaykin, said his client was never a Cuban intelligence agent and is not a supporter of Castro.

“His involvement with the Cuban intelligence agency was the result of idealism and naivete,” Chaykin said.

Jane Moscowitz, attorney for Elsa Alvarez, said her client played a far lesser role. “Her offence is being a wife,” Moscowitz said.