Italian scientists believe they have uncovered a 400-year-old murder. Historians have long suspected that Francesco de' Medici, Grand Duke of Tuscany, and his second wife Bianca Cappello did not die of malaria but were poisoned — probably by Francesco's brother, Cardinal Ferdinando de' Medici, who was vying for the title.Now, forensic and toxicology experts at the University of Florence report evidence of arsenic poisoning in a new study published in the British Medical Journal.As rulers, art connoisseurs and financiers of kings, the Medici family flourished for centuries in the rough and tumble alliances of old Europe, providing four popes and...