The postmortem made one thing patently clear: something the victim had said or done had enraged her killer to the point of maniacal fury. Ironically, despite her grievous wounds, Betty Berry had not succumbed to the multiple head injuries. Her cause of death was drowning.

Her lungs were completely filled with water and death would have come quickly, as it always does with freshwater drowning, as the human bloodstream, with a higher salt content than lake water, actually sucks water into the blood.

Dr. Wilson determined that the victim had died at about 2 a.m. on the morning of July 4 with an hour’s leeway in either direction. A test...