Medical specialists have disclosed that the pig heart transplanted into a human patient in a groundbreaking procedure in January was infected with a porcine virus that may have led to the patient’s death. David Bennett Sr., 57, died about 40 days after the transplant. “We are beginning to learn why he passed on,” said the transplant surgeon, Bartley Griffith, from the University of Maryland School of Medicine. Griffith suggested the virus “maybe was the actor, or could be the actor, that set this whole thing off.” The select pig had been raised in a controlled environment by Revivicor, a biotech company, that was responsible for its health, MIT Technology Review reports. “If this was an infection, we can likely prevent it in the future,” Griffith said, hopeful that future transplants could be successfully performed.