On this much, the police and Girvies Davis can agree. On Dec. 22, 1978, Charles Biebel, an 89-year-old retired farmer, was found slumped in his wheelchair in a mobile home in Belleville, Illinois, his chest shredded by two bullet wounds. The following August, Davis, a 20-year-old alcoholic with a childhood history of brain damage and suicide attempts, and an arrest record dating back to age 8, was picked up for the armed robbery of an auto-parts store in East St. Louis. Ten days later, Davis confessed to 11 crimes, among them the Biebel murder.
The validity of his confession, however, is...