A former Alabama state trooper has pleaded guilty to the 1965 murder of a Black civil rights activist, a momentous shooting-death that spurred marches in Selma and Montgomery and contributed to the eventual enactment of the Voters Rights Act.

James Bonard Fowler, 77, pleaded guilty to second-degree manslaughter in the death of Jimmie Lee Jackson on Nov. 15—two weeks before he was scheduled to go to trial for the murder.

“He’s almost 80, so if this case would have been delayed some more, there was a chance he would have died before justice could have been done,” Perry County district attorney Michael Jackson told reporters after the plea announcement.

Fowler was sentenced to six months in jail and six months unsupervised probation. He is to report to a Geneva County prison by Dec. 1, his attorney told reporters.

The now-elderly White man was accused of shooting Jackson in the stomach during a civil rights protest in a Marion, Ala. restaurant on the night of Feb. 18, 1965. Fowler said in a 2004 interview with a local newspaper that Jackson reached for his gun, and he fired in self-defense. Witnesses said Jackson was trying to protect his mother and grandfather, who had been viciously clubbed by officers.

Jackson’s death prompted a protest march on Selma, an event now remembered as “Bloody Sunday,” in which police brutally attacked marchers trying to cross the Edmund Pettus Bridge over the Alabama River. Martin Luther King Jr. spoke at Jackson’s funeral and later led the Selma-to-Montgomery marches along with others that attracted white backlash.

The images that were recorded by newspaper and television coverage of the clashes between civil rights advocates and the White resistance galvanized national attention against segregation and prompted the passage of the Voting Rights Act.

Fowler apologized to Jackson’s family after entering his plea. “I was coming over here to save lives,” Fowler told the family. “I didn’t mean to take lives and wish I could re-do it.”

Jackson’s sister, Emma Jean Jackson, told The Anniston Star she was happy with the plea.

“This is closure for the family,” she said. “That’s the most important thing, and I think it is what he would have wanted. His birthday is coming up soon, and I really think this would be Jimmie’s best birthday present ever.”