Charles Edmund Cullen (born February 22, 1960) is an American serial killer who confessed to murdering up to forty patients during the course of his sixteen-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.