The centuries-old mystery surrounding the deaths of Grand Duke Francesco I de’ Medici and his wife, Bianca Cappello, in 1587 may finally be solved by new DNA analysis. While historical accounts and symptoms initially pointed to malaria, rumors of assassination, implicating Francesco's brother Ferdinando, persisted due to family rivalries and Ferdinando's proximity to the couple before their deaths.

New DNA research, led by Serena Tucci of Yale University and the University of Pisa, analyzed skeletal remains of Francesco and his brother Giovanni. The study found genetic traces of the malaria parasite, *Plasmodium*, in Francesco's remains, identifying two species of malaria. Malaria was also detected in Giovanni's remains. This genetic evidence provides a more definitive answer than previous paleo-immunological studies.

While the DNA analysis strongly supports malaria as the cause of death, some researchers, like Donatella Lippi, maintain that poisoning cannot be entirely ruled out, citing historical accounts of arsenic poisoning symptoms and the preservation of Francesco's body. However, the genetic evidence significantly reduces the margin for speculation, suggesting malaria was the primary culprit, potentially exacerbated by other factors.