Charles Edmund Cullen (born February 22, 1960) is a former nurse who is the most prolific serial killer in New Jersey history and suspected to be the most prolific serial killer in American history. He originally told authorities he killed up to 40 patients during the course of his 16-year nursing career.[2] But in subsequent interviews with police, psychiatric professionals, and journalists Charles Graeber and Steve Kroft[3], it soon became clear that he had killed many more, whom he could not specifically remember.[4] Experts have estimated that Charles Cullen may ultimately be responsible for some 400 murders, which would make him the most prolific serial killer in American history.[1]