On April 23, 1963, William L. Moore was found dead on U.S. Highway 11 near Attalla, Alabama—only four days shy of his 36th birthday. Mr. Moore, a white man, was in the midst of a one-man civil rights march to Jackson, Mississippi, to implore Mississippi Governor Ross Barnett to support integration efforts. He wore signs that read: “End Segregation in America, Eat at Joe's-Both Black and White” and “Equal Rights For All (Mississippi or Bust).”

Mr. Moore, a resident of Baltimore, Maryland, was a member of the Congress of Racial Equality (CORE) and had staged other lone protests in the past. On his first protest, he walked to Annapolis, Maryland, from Baltimore. On his second march, he walked to the White House. For what proved to be his final march, Mr. Moore planned to walk from Chattanooga, Tennessee, to Jackson.

About 70 miles into the march, a local radio station reporter named Charlie Hicks interviewed Mr. Moore after the radio station received an anonymous tip of his whereabouts. After the interview, Mr. Hicks offered to drive Moore to a hotel where he would be safe, but Mr. Moore continued on his march instead. Less than an hour later, a passing motorist found his body. Mr. Moore had been shot in the head with a .22-caliber rifle that was traced to Floyd Simpson, a white Alabamian. Mr. Simpson was arrested but never indicted for Mr. Moore's murder.

When activists from the Student Nonviolent Coordinating Committee (SNCC) and CORE attempted to finish Mr. Moore’s march using the same route, they were beaten and arrested by Alabama state troopers.