(CNN) -- James Ford Seale, a reputed former member of the Ku Klux Klan convicted in the 1964 abduction and killings of two African-American teenagers in Mississippi, has died in federal prison, the Federal Bureau of Prisons said. He was 75.
Seale died on Tuesday in the Federal Correctional Institution at Terre Haute, Indiana, said bureau spokesman Chris Burke, but he did not provide further details.
A jury in 2007 convicted Seale, a former sheriff's deputy, of kidnapping and conspiracy to commit kidnapping in the disappearances of Charles Eddie Moore and Henry Hezekiah Dee, both 19. The bodies of both youths were found in a backwater area of the Mississippi River. Seale was serving three life sentences.
Seale was not tried for murder, but prosecutors alleged he and fellow Klansmen conspired to abduct, beat and murder Dee and Moore in May 1964. An indictment accused Seale and his cohorts of picking up the two men hitchhiking and driving them into the Homochitto National Forest in southwest Mississippi's Franklin County, where the teenagers were beaten and interrogated at gunpoint.
Dee and Moore were then bound with duct tape, and weighted down by an engine block and a railroad rail, authorities said. The FBI alleged the two were still alive when they were thrown into the Old Mississippi River, where they drowned. Their decomposed bodies were found two months later during a search for three other missing civil rights workers -- a case that would later be known as the Mississippi Burning Case.
The slayings were officially unsolved until Seale was indicted in 2007, although he had been long suspected in the case. He and another man were arrested in 1964, but released on bond and never tried. The FBI turned the case over to local authorities, and the investigation was dropped after a justice of the peace said witnesses had refused to testify.
The case was revived in 2007 after Moore's brother, Thomas Moore, discovered Seale was still alive while visiting Franklin County, where he was helping research the case for a Canadian Broadcasting Corporation documentary. Moore told CNN in January 2007 that he then gave the U.S. attorney for the Southern District of Mississippi the FBI files on the case, which he had obtained from a reporter. U.S. Attorney Dunn Lampton helped form a task force that led to Seale's indictment.
Seale was the first and only person convicted in the Moore and Dee case, the Justice Department has said.
Seale's conviction was overturned, then reinstated, by federal appeals courts amid a legal battle over whether the statue of limitations had expired for his crimes. The battle wound up at the U.S. Supreme Court, which in November 2009 let stand a lower court ruling that the statute of limitations had not expired.
In his appeal, Seale claimed the statute of limitations expired five years after the crime. The confusion arose out of the fact that kidnapping could be considered a capital offense in 1964 and had no time limit for prosecution. In 1968, the high court eliminated the federal death penalty for that crime, and Congress changed the law to reflect that ruling four years later. But lawmakers in 1994 reinstated kidnapping as being death penalty eligible.
CNN's Dave Alsup and Bill Mears contributed to this report.