BANGOR, Maine — A federal court has dismissed a Stockton Springs woman’s claim against the nation of Cuba because her lawyer has been unable to verify serving papers to the controversial Caribbean country. But the woman’s Lewiston lawyer said the U.S. court action is procedural only and that her case remains viable.

Sherry Sullivan believes her father, Geoffrey Sullivan, was shot down while flying over Cuba in 1963, captured, tortured and held for 10 or more years. The Cuban military then executed him as a spy, she believes, based on extensive research.

Sullivan won a $21 million judgment against Cuba in state court in 2009. With interest, that judgment is now worth almost $26 million. She filed suit in federal court earlier this year to enforce the judgment.

On Wednesday, Dec. 26, U.S. District Court Judge George Singal dismissed the case because Sullivan’s lawyer has been unable to serve the Cuban government with the judgment. The dismissal “without prejudice,” according to Sullivan’s attorney David Van Dyke, is the court saying, in essence, “You haven’t been able to achieve service. Take a break, come back to us when you’ve achieved it.”

The U.S. broke off diplomatic relations with the authoritarian regime in 1961, and imposed isolating travel restrictions and an economic embargo.

“Serving,” or proving that the Cuban government has been notified of the judgment, has been a daunting task, Van Dyke said Thursday.

Documents from the Waldo County Superior Court judgment are believed to have been delivered to the government through the Swiss embassy in 2008, but were ignored.

Sending documents directly to Cuba resulted in them being blocked by its customs officials. “They’re not stupid,” Van Dyke said.

Efforts also have been made to make the service through Spain, the United Kingdom, Canada and other embassies with which Cuba has relations. Van Dyke said service was even attempted on Cuban cargo ships, but to no avail.

If the United States normalizes relations with Cuba, Van Dyke and Sullivan said Thursday, this and other judgments likely would be settled, though the actual payments might be significantly less.

Sullivan had not heard about the court ruling until she was contacted by the Bangor Daily News on Thursday. She said she remains committed to the fight.

“It never was about the money,” she said. “I’d like to have my father’s remains returned.”

Sullivan believes she has nailed down most of the details of her father’s disappearance. He was 29, an Air Force veteran with a commercial pilot’s license serving in the Army National Guard. He then met Alexander Irwin Roake Jr., a New York newspaperman who was believed to be an operative of the Central Intelligence Agency. Roake reportedly ran guns to Cuba.

Sullivan took off from Mexico in a twin-engine plane, accompanied by Roake, before he disappeared.

The official story was that the plane disappeared over Central America. The Department of Veterans Affairs has listed Geoffrey Sullivan as “missing in action.”

A month earlier, the men allegedly had taken part in a bombing run over Cuba in a refurbished B-25 bomber, an act that received widespread newspaper coverage. Both men were identified as having been involved.