A physicist and his wife, who both once worked at the Los Alamos National Laboratory in New Mexico, were arrested Friday and charged with a criminal conspiracy to help Venezuela build an atom bomb.

The arrests of P. Leonardo Mascheroni and Marjorie Roxby Mascheroni and a 22-count indictment came after a sting operation by the Federal Bureau of Investigation from 2008 to 2009. A raid on the couple’s home in Los Alamos last October hauled away cameras, computers and hundreds of files.

“If I were a real spy,” Dr. Mascheroni told a reporter at the time, declaring his innocence, “I would have left the country a long time ago.”

After their arrests on Friday, the couple appeared in federal court in Albuquerque. They were charged with handing over secret weapons information to an F.B.I. agent posing as a Venezuelan spy. The government did not accuse the Venezuelan government, or anyone working for it, of seeking weapons secrets.