But he was perhaps best remembered for his inquiry to free a young man from prison in a matricide case, starting with only the suspicions of the playwright Arthur Miller, who lived a few miles from the crime scene. “He said he thought that Peter Reilly could have murdered his mother, but he wondered how he could have done it without getting blood on his clothes,” Mr. Corry wrote in 1975. “The playwright said it bothered him.” By then, the case was two years cold. Mr. Reilly had been convicted of killing his mother, Barbara Gibbons, in their Canaan, Conn.,...