At 9:00 on the morning of March 6, 1963, in the quiet St. Paul neighborhood of Highland Park, Mrs. Fritz Pearson glanced out her window and saw something almost unimaginable: slumped on the front steps of the home across the street was a woman, partially clothed in a blue bathrobe and bloodied beyond recognition. The woman, Mrs. Pearson would come to learn, was her beloved neighbor Carol Thompson, wife and mother of four.

Earlier that morning, T. Eugene Thompson, known to friends as "Cotton," dropped his son off at school and headed to the office, where he worked as a criminal...