By Emanuella Grinberg and Jamiel Lynch CNN

(CNN) -- Elbert Williams may not be as well-known as Medgar Evers, James Chaney or other American civil rights activists who were killed in their quest for justice and equality.

No autopsy was performed on Williams. No one was charged with a crime. It's not even clear where his body was buried.

But that may change soon.

The investigation into Williams' death almost 80 years ago has been reopened, a Tennessee prosecutor said Thursday. Williams is thought to be the first NAACP member to be killed for his civil rights work.

"We cannot do all in 2018 that should have been done in 1940, but justice and historic truth demand that questions about the cause of Elbert Williams' death, and the identity of his killer(s), that should have been answered long ago, be answered now if possible," Garry G. Brown, District Attorney of Tennessee's 28th Judicial District, said in a statement.

Who was Elbert Williams?

Williams was born in Haywood County, Tennessee in 1908 to sharecropper parents, according to retired lawyer Jim Emison, who is writing a book about Williams' life and death.

Williams received his education in the African-American church that served as the school for black children in the county. There he met his wife, Annie. The couple married in 1929 and both got jobs at Sunshine Laundry. She worked as a presser and he as a fireman who kept the boiler going.

A founding member of the Brownsville, Tennessee NAACP chapter in 1939, Williams was involved in efforts to register black voters.

On June 20, 1940, police kidnapped him from his home and interrogated him in the city jail about whether he was planning an NAACP meeting.

Three days later, Williams' body was found, beaten and bruised, in the Hatchie River, six miles south of the city. His widow said he appeared to have two bullet wounds in his chest, according to Emison.

A hastily assembled coroner's inquest at the riverbank determined the cause of death "foul means by parties unknown." An immediate burial was ordered before an autopsy or external medical examination was performed. Williams' body is believed to be buried in an unmarked grave in Taylor Cemetery in Haywood County.

In August 1940, a special county grand jury ruled the death a homicide, Brown said. The US Justice Department later said the murder was "undoubtedly" a violation of federal civil rights laws, but no charges were brought. Tennessee has no statute of limitations on first-degree murder.

"There is no expiration date on the truth or justice. Elbert Williams, like so many other relatively unknown heroes of the civil rights movement gave their lives to exercise the most basic foundation of our democracy -- the vote," NAACP Communications Director Malik Russell said.

'I hope it's done right'

A historical marker honoring Williams was unveiled near the town square in Brownsville on June 20, 2015. Otherwise, no progress has been made in the case.

It is being reopened under the state's new Civil Rights Crimes Cold Case Law, which mandated a survey of cold crimes and referral for prosecution of those deemed "viable." Experts with the forensic anthropology department at the University of Tennessee have volunteered to locate the grave and exhume the remains for examination, Brown said.

Emison said he has been hoping that the case would one day be reopened. Even if no one faces charges, finding his body and giving him a proper burial would be a measure of justice, he said.

"I hope it's done right," he said. "I hope it becomes a model. A model for the South and a model for the nation."

The retired lawyer stumbled upon Williams' story while he was researching a court case online and found an article about Depression-era lynchings in middle Tennessee. He had never heard Williams' name before, and that surprised him as someone who had lived in the area his whole life. He asked other lawyers and judges if they knew about the case and found out that he wasn't alone, he said.

He started research thinking he would write an article. Six years later, he's working toward a book.

"We will never heal the wounds inflicted until we acknowledge them. Discover their depth. Apologize and try to make them right," he said. "That is what I hope happens."

CNN's Ray Sanchez contributed to this report.

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