Ana Montes, former U.S. analyst convicted of spying for Cuba, is released from prison

Ana Montes, a former U.S. defense intelligence analyst who was convicted of spying for Cuba, has been released from federal prison in Fort Worth, Texas.

Montes, 65, was released on Friday after serving a majority of her 25-year sentence, according to a spokesman for the Federal Bureau of Prisons, adding that her early release was based on good behavior.

Montes was an analyst with the Defense Intelligence Agency for 16 years, starting in 1985. During her career, she was highly regarded for her expertise about Cuba. But under the radar, Montes used coded messages and water-soluble paper to disclose classified information. Among the secrets she gave to the Cuban government were the identities of four U.S. spies in Cuba.

In 2002, Montes pleaded guilty to conspiracy to commit espionage on behalf of the Cuban government.

During her sentencing, Montes told the judge and courtroom that she had chosen to follow her "conscience rather than the law."

"I believe our government's policy toward Cuba is cruel and unfair, profoundly unneighborly, and I felt morally obligated to help the island defend itself from our efforts to impose our values and our political system upon it," Montes said, according to The Washington Post.

Montes memorized classified information to disclose

Montes began working for the U.S. government in 1984 as a clerk at the Department of Justice. According to the FBI's biography of Montes, she was openly critical of the U.S. government's policies toward Central America. Her disapproval eventually caught the attention of Cuban operatives who recruited her to the Cuban Intelligence Service.

A year later, with the help of other co-conspirators, Montes was hired at the Defense Intelligence Agency, where she would have access to classified national defense information. She served as an intelligence analyst for 16 years, up until her arrest in 2001. Montes became one of the DIA's top aides on Cuba, the FBI said.

Montes' spying went under the radar for years — largely because she never stole any government documents. Instead, Montes memorized sensitive information and typed them up on her laptop when she arrived home, according to the FBI.

Montes would also get her instructions from Cuba through encrypted messages on a shortwave radio and write down the details on special water-soluble paper that could quickly dissolve.

The Justice Department said among the government secrets Montes disclosed were the identities of U.S. spies in Cuba.

Colleagues slowly grew more suspicious of Montes

Despite Montes' careful strategy, colleagues slowly became suspicious of her, partly because they knew her foreign policy views, according to the FBI.

Eventually, in 1996, one co-worker raised the alarm about Montes to a security official who then interviewed her. Though she admitted nothing, that interview later became a crucial piece in the FBI's search to uncover a Cuban agent operating in Washington.

In 2001, Montes was arrested in her office at the DIA headquarters.

The FBI said Montes' motivation for spying was "pure ideology" as she did not accept any money for sharing classified information, except some reimbursements.