Charles Edmund Cullen is an American serial killer who confessed to murdering up to 40 patients during the course of his 16-year career as a nurse in New Jersey. However, in subsequent interviews with police, psychiatrists, and journalists, it became apparent that he had killed many more, whom he could not specifically remember by name, though he could often remember details of their murders. Experts have estimated that Cullen may ultimately be responsible for 400 deaths, which would make him the most prolific serial killer in recorded history. He has 29 confirmed victims.