From a small weekly newspaper in Louisiana, Mr. Nelson reopened unsolved killings from the civil rights era and became a Pulitzer Prize finalist.

We remember Stanley Nelson, the editor of a small-town weekly newspaper in Louisiana, who exposed secrets about unsolved murders by the Ku Klux Klan. Nelson died this week at the age of 69.

In 1925, 25,000 members of the Ku Klux Klan marched down Pennsylvania Avenue in Washington. Never before had so many men in ...