In the spring of 1993, Morris Gauger and his wife, Ruth Gauger, were bludgeoned and stabbed to death on their family farm near Richmond, Illinois. Their son, forty-year-old Gary Gauger, phoned 911 after he and a friend discovered his father's body on the floor of the antique motorcycle shop located at the farm. Police became suspicious when they arrived to find an oddly serene Gary Gauger, who calmly tended to his vegetable garden during the investigators' search for evidence. After discovering the body of Ruth Gauger—but no signs of struggle or attempted robbery—police subjected Gauger to twenty-one hours of intensive questioning. During this interrogation, Gauger later reported, detectives claimed that they had a "stack of evidence" proving that he had committed the murders. It did not occur to Gauger that his accusers might be lying.

Gauger, a pot smoker and reformed alcoholic at the time of...