Travis Clinton Hittson was sentenced to death in 1993 after the killing of Conway Utterbeck, who was beaten with a baseball bat and shot. His body parts were then hidden in Georgia and Florida.
The two were on leave from their ship and staying in Warner Robins, the Telegraph reported.
Another shipmate, Edward Vollmer of Warner Robins, was also charged with murder but reached a plea bargain and was sentenced to life in prison.
U.S. Middle District Court Judge Marc Treadwell ruled that Vollmer was more culpable in the crime, and convinced Hittson to participate in it.
The state must hold a new sentencing hearing or agree to a lesser sentence for Hittson, who is from Fremont, Neb., the judge ruled.
Houston County District Attorney George Hartwig could not be reached for comment, the Telegraph reported.
Vollmer had told Hittson he wanted to kill Utterbeck because Utterbeck was planning to kill them, according to the judge’s ruling. Utterbeck was from Humansville, Mo.
After the slaying, they dismembered the body and cleaned up the crime scene, prosecutors said.
Some of Utterbeck’s remains were placed in garbage bags. His torso was buried in Houston County and found later by loggers.
After the killing, Hittson and Vollmer drove back to Pensacola, Fla., where they were stationed, and buried the rest of the remains, authorities said.