For almost 10 years, a retired Cuban Air Force pilot, Lt. Col Luis Raúl González-Pardo, traveled between Cuba and Florida, entering the United States without revealing his military history and going unnoticed.

That was until his arrest in November, when he was accused of failing to disclose on U.S. immigration forms that he had been a member of the Cuban Air Force for nearly 30 years.

He pleaded guilty in January to immigration fraud charges and is scheduled to be sentenced on May 28 in federal court in Jacksonville, Fla.

Mr. González-Pardo, 65, who is jailed, could receive a maximum sentence of 10 years.

On Wednesday, Mr. González-Pardo faced even more serious charges when he was named as a defendant in a federal indictment against the former president of Cuba, Raúl Castro, and four other members of the Cuban Air Force.

All are charged with conspiracy to commit murder in a notorious case involving the killing of three Americans and a U.S. resident, all of Cuban descent, who were members of Brothers to the Rescue, a group of pilots that scoured the seas looking for rafters fleeing Cuba.

All four died in February 1996 when Cuban fighter jets shot down two civilian planes operated by the group over international airspace in the Straits of Florida. A third plane escaped and landed safely in Miami.