The day after his arrest, he made another suicide attempt. Cullen took two months off from work and was treated for depression in two psychiatric facilities. However, he attempted suicide twice more by the end of the year. That September, a 91-year-old cancer patient at Warren Hospital reported that Cullen, who was not her assigned nurse, had come into her room and injected her with a needle. She died the next day. Her son protested that her death was not natural, and the hospital administered a lie detector test to Cullen and several other nurses, which he passed. Cullen continued to work at Warren until the following spring. Cullen began a three-year stint in the intensive care unit of Hunterdon Medical Center in Flemington, New Jersey. He claimed that he did not harm anyone during the first two years at Hunterdon. However, hospital records for that period had been destroyed at the time of his arrest in 2003. Cullen admitted to murdering five patients between January and September 1996, again with overdoses of digoxin. He then found work at Morristown Memorial Hospital but was soon fired for poor performance. Cullen remained unemployed for six months and stopped making child support payments. After seeking treatment for depression in the Warren Hospital emergency room, he was briefly admitted to a psychiatric facility. In February 1998, Cullen was hired by the Liberty Nursing and Rehabilitation Center in Allentown, Pennsylvania, where he staffed a ward of respirator-dependent patients. There he was accused of giving patients drugs at unscheduled times. He was fired after being seen entering a patient's room with syringes in his hand, an encounter that left the patient with a broken arm. Cullen caused a patient's death at Liberty Hospital, which was blamed on another nurse. After leaving Liberty, Cullen was employed at Easton Hospital from November 1998 to March 1999. On December 30, 1998, he murdered yet another patient. A coroner's blood test showed lethal amounts of digoxin in the patient's blood but an internal investigation within Easton Hospital was inconclusive; evidence did not definitively point to Cullen as the murderer. Even with his history of mental instability and the number of deaths during his employment at various hospitals, Cullen continued to find work because of a national shortage of nurses. Additionally, no reporting mechanism yet existed to identify nurses with mental health or employment problems. Liability concerns made hospitals unwilling