High Quality Content by WIKIPEDIA articles! 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. Cullen told authorities in December 2003 that he could specifically recall the murder of perhaps 40 patients during the 16 years he worked at 10 hospitals in New Jersey and Pennsylvania. As part of his plea agreement, Cullen has been working with law enforcement officials to identify additional victims. He originally told authorities he killed up to 40 patients during the course of his 16-year nursing career. But in subsequent interviews with police, psychiatric professionals, and the only journalist with whom he had ever granted interviews, Charles Graeber, it soon became clear that he had killed many more, whom he could not specifically remember. 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.