Employes of Systems Control Inc., a defense contractor in Palo Alto, Calif., should have guessed something was wrong with Ruby Schuler, the company president's secretary.

In 1981, Schuler was sipping vodka at her desk before lunch, jetting to weekends in Mexico, and once was seen with a stack of $100 bills at a bank. But coworkers didn't pry.

Schuler had a secret. For years she'd been stealing documents from the office and copying them at home. Her husband, James Harper, an electronics engineer, was selling them to Polish intelligence.

Between 1979 and 1981 Harper met a dozen times with Polish agents in Warsaw, Vienna and Mexico, and received $250,000.

But Harper was playing another tricky game. In 1981 he started meeting with a lawyer -- without identifying himself -- and tried to negotiate immunity from prosecution. For two years Harper sent the FBI and CIA anonymous messages through the attorney in an effort to become a double agent.

But with the help of a source within Polish intelligence, investigators identified Harper. After his 1983 arrest, investigators found numerous classified documents in his safety deposit box in Tijuana. Schuler had died before Harper's arrest.

The material Harper sold dealt with U.S. defenses against ballistic missile attack and the survivability of Minuteman missiles. The Army described Harper's national security damage as "beyond calculation."

In April 1984 Harper pleaded guilty to selling classified documents to the Poles. Federal Judge Samuel Conti in San Francisco, noting Harper expressed no sorrow or regret, sentenced him to the maximum, life in prison.

"You are a traitor to your country," Conti said, "who committed the crime not for any political reasons, but for greed."