The grand jury records from the 1946 lynching of two black couples in Georgia cannot be released despite their great historical significance, a federal appeals court said.

The 11th U.S. Circuit Court of Appeals in Atlanta ruled  8-4 that federal judges don’t have authority to disclose grand jury records for reasons other than those provided for in the rules governing grand jury secrecy.

Roger and Dorothy Malcom and George and Mae Murray Dorsey were riding in a car on a rural road in July 1946 when a white mob stopped it at Moore’s Ford Bridge, overlooking the Apalachee River. The mob dragged the young black sharecroppers to the river’s edge and shot them to death.

The slayings shocked the nation, and the FBI descended upon the rural community in Walton County, about 50 miles (80 kilometers) east of Atlanta. Following a monthslong investigation, more than 100 people reportedly testified before a federal grand jury in December 1946, but no one was indicted.

Historian Anthony Pitch wrote about the killings — “The Last Lynching: How a Gruesome Mass Murder Rocked a Small Georgia Town” — and continued his research after the book’s 2016 publication. He learned transcripts of the grand jury proceedings, once thought to have been destroyed, were stored by the National Archives.