«Seasons of Death» by M.K. Wren

In 1940 Leland Langtry ran off with his redheaded secretary and $10,000 in company funds… Or so everyone believed… Forty years later, Langtry's remains are found in a boarded-up silver mine tunnel. And as the knife still jammed between his ribs had belonged to his partner in Lang-Star Mining, Tom Starbuck-also long since dead-a jury decided that Tom had killed Langtry. But Tom's widow, Delia, resists that verdict and persuades that very private investigator Conan Flagg to find the real murderer-an impossible job made tougher by the curious reticence of nearly everyone in town whenever Leland Langtry is mentioned…