Former Mississippi governor William Waller Sr., who as a district attorney twice unsuccessfully prosecuted the man eventually convicted of killing civil rights leader Medgar Evers, died of a heart ailment Nov. 30 at a hospital in Jackson, Miss. He was 85.

Mr. Waller’s law office confirmed the death. Mr. Waller, a Democrat, served as governor from 1972 to 1976, a time when Mississippi governors were limited to one term.

Mr. Waller also served as district attorney in Hinds County in the 1960s and twice tried to get a conviction against Byron De La Beckwith for Evers’s assassination in 1963; Evers was the Mississippi field secretary for the NAACP.

In 1994, prosecutor Bobby DeLaughter was able to secure a guilty verdict when blacks were able to serve on the jury. De La Beckwith died in 2001 while serving a prison term for murder.

“Under the circumstances, I think we did the very best job that we could,” Mr. Waller said in a 2001 interview with the Associated Press. “I think the jury was taking the position that they wanted to be convinced beyond a reasonable doubt, to a moral certainty, and a lot of jurors interpret that as eyewitness, direct proof.”

William Waller Sr, arrives at the court house in Jackson, Miss., in January of 1964. (AP)

Charles Evers, the brother of Medgar Evers, said it’s unlikely that Beckwith would have been convicted 30 years later if Mr. Waller had not laid the foundation with the two trials in the 1960s.

“He tried Byron De La Beckwith twice, which was unheard of in those days to prosecute a white man for doing anything to a black man,” Evers said. “He did everything he could. He just couldn’t get a conviction.”

As governor, Mr. Waller vetoed funding for a segregationist watchdog agency, the Mississippi Sovereignty Commission, putting it out of business. He also appointed the first black member of the state College Board, Robert Walker Harrison of Yazoo City.

During Mr. Waller’s administration, Mississippi’s three historically black colleges, Jackson State, Alcorn State and Mississippi Valley State, were elevated to university status. Two smaller, predominantly white schools, Delta State College and Mississippi State College for Women, got the same boost.

When he took office, Mr. Waller found the Governor’s Mansion, built in 1841, in such bad shape that there was talk of turning it into a museum and finding an executive home in the suburbs.

The Wallers led an effort to restore the Mansion as a place for first families to live and for hosting ceremonial gatherings. They lived in the house only a few months after it reopened.

He returned to that law practice once his term as governor ended, interrupting it to run unsuccessfully for the U.S. Senate in 1978 and again for governor in 1987.

William Lowe Waller was born Oct. 21, 1926, and grew up outside Oxford, Miss. He graduated from Memphis State University in Tennessee and received a law degree from the University of Mississippi.

He served in the Army Counterintelligence Corps during the Korean War, then established a law practice in Jackson.

Survivors include his wife of 61 years, Carroll Overton Waller; four sons, including Mississippi Supreme Court Chief Justice William Waller Jr.; and 14 grandchildren. A daughter, Gloria, died in 1981.

— Associated Press