Stanley Nelson, a crusading small-town journalist with a passion for probing unsolved Ku Klux Klan murders, died on June 5 at his home in DeRidder, La. He was 69.

His death was confirmed by his daughter, Tessa Nelson Granger. She did not specify a cause but said he had recently had surgery.

Mr. Nelson’s efforts to solve a particularly vicious Klan murder — the arson death of the Black owner of a shoe-repair shop in Ferriday, La., in 1964 — made him a Pulitzer Prize finalist in 2011; earned him the esteem of the small but ardent band of journalists dedicated to civil-rights-era cold cases; and were the inspiration for a central figure in the Mississippi writer Greg Iles’s best-selling novel “Natchez Burning” (2014).

“In his quest for truth, Stanley led me through the secret pasts of our home states — Mississippi and Louisiana — among men who lived in the shadow of crimes that had no statute of limitations,” Mr. Iles wrote in The Natchez Democrat last week.

Natchez, Miss., is just across the river from Ferriday, where Mr. Nelson was the editor of The Concordia Sentinel, a weekly with a three-person newsroom and a circulation of 5,000. The Louisiana town, around 200 miles northwest of New Orleans with a population of about 3,000, is best known as the hometown of the rock ’n’ roll pioneer Jerry Lee Lewis and his preacher cousin, Jimmy Swaggart.

During the 1960s, Ferriday was also known for its virulent Klan presence and for being a rough sawmill town — “the meanest” in Louisiana, the New Orleans civil rights attorney Jack Martzell once said. It was a place civil rights workers feared.