Andrea D. Lyon has represented defendants in 138 homicide cases. She’s not lost one of her 19 death penalty cases.The longtime death penalty attorney and former Valparaiso University Law School dean opened her own practice last month under the name Lyon Law.The firm is located at 53 W. Jackson Blvd.Lyon spent more than 14 years as a Cook County public defender starting in 1976. She became chief of the office’s Homicide Task Force and was the first woman in Illinois to serve as lead attorney in a death penalty …