Saint Barnabas Hospital’s investigation of the insulin incidents and dismissal of Cullen

Saint Barnabas Hospital’s investigation of the insulin incidents and dismissal of Cullen exposed a pattern of unexplained insulin poisoning, but never produced a definitive finding against Charles Cullen before he left the hospital. The inquiry moved from contaminated IV bags and repeated patient crises to internal safeguards and a police referral that went nowhere. Its unresolved ending became more troubling in light of later-recovered records describing conduct consistent with the suspected method.

The Pattern in the IV Bags

The investigation sharpened when a bag connected to Fred Belf tested positive for insulin. Belf had received heparin at 7 a.m.; by noon he was vomiting and could not keep down orange juice. His doctors added intravenous dextrose, and the two drips continued side by side until the connection between the heparin bags and the symptoms was made the next evening. Once nurses disconnected the heparin, Belf quickly began to feel better. They sealed the bag in sterile plastic and sent it for testing.

The laboratory result was accompanied by an unusual physical clue: microscopic examination found tiny needle punctures across the bag, including three along its edges. Bags could be punctured while being connected to a stopcock, but not ordinarily around their perimeter. The pattern suggested repeated, intentional tampering in the Saint Barnabas Medical Center storage room. Investigators also had two bags as evidence and accounts of similar crises involving Anna Byers and Belf.

Reviewing records across the intensive care, critical care, and cardiac units revealed recurring episodes of unexplained insulin crashes. The cases were scattered across units and shifts, and emergency codes sometimes overlapped so that nurses had to leave one crisis to respond to another. Laboratory results showed exceptionally high insulin levels in the affected patients, with much of the insulin being foreign to the body rather than naturally produced. Yet the records contained neither a prescription for insulin nor a nursing notation that it had been administered. An ordinary medication or charting error remained possible, but the absence of both an order and a record made a simple explanation harder to sustain.

From Internal Review to a Suspect

Thomas Arnold brought the findings to Joe Barry, Saint Barnabas’s senior vice president in charge of security and a former police officer. After they ruled out patients’ visitors, the investigators compared nursing schedules with the times of patient crises. Three nurses had been working at every code; among them, Cullen drew the most attention. His work as a floater across several units, often on last-minute call-ins, made it difficult to match his activity to particular incidents, while the patients’ complex illnesses made it difficult to prove that an unexplained insulin spike caused a specific crisis or death.

The hospital’s review widened, but the investigators could not turn the accumulating irregularities into certainty. They prepared timelines and mortality rates, interviewed physicians, staff, and families, and installed stop-motion cameras in the medication storage room for several weeks. They also introduced a more stringent insulin sign-out procedure. When two more patients in the cardiac care unit suffered unexplained hypoglycemia in October and were found connected to insulin-tainted IV bags, suspicion deepened, but proof remained elusive.

A later-recovered incident report described Cullen checking a patient’s insulin levels repeatedly at inappropriate intervals. Another recorded that, after his shift, he left an unlabeled IV hanging in place of the prescribed potassium chloride solution. When contacted at home, he appeared apathetic and said that if the bag was hanging there, it must contain the prescribed solution. The report could not establish what the bag actually contained. Its circumstances were more troubling than a simple dosage mistake: Cullen had withheld the prescribed medication, substituted an unlabeled bag, and pinched off the line so that the next nurse would start the drip. Later, Cullen admitted to randomly spiking saline bags with insulin and sometimes arranging for another nurse to infuse them while he was absent; the contents of this particular bag nevertheless remained unknown.

The Police Referral and Its Limits

By early 1991, Arnold and Barry concluded that the inquiry needed outside help. On March 5 they presented the case to the Livingston police chief over lunch. They had patients, physical evidence of IV tampering involving dangerous drug doses, and a strong suspect among the hospital staff. The chief declined to pursue it, saying he did not think the evidence would allow him to do anything and that the hospital should handle the matter internally. The investigators could not yet prove their suspicions themselves, so the responsibility remained with the hospital.

That decision left Saint Barnabas trying to catch the person responsible without an external investigation. The cameras, interviews, and tighter insulin controls did not resolve the cases. The events were difficult to unify: they appeared across wards and shifts, and Cullen’s irregular schedule complicated comparisons. The inquiry could identify a disturbing cluster and a plausible suspect, but the distinction between a pattern worth investigating and evidence sufficient to establish individual responsibility remained consequential.

The Form, the Departure, and the Unresolved Record

The new insulin procedure also exposed how little information reached bedside nurses. Under the insulin adjustment form, nurses had to estimate how much remained in a vial and attach their electronic signatures to that estimate. Amy Loughren considered the measurement unreliable and refused to sign. Her manager would not explain why insulin was suddenly being handled with heightened controls, leaving Loughren to infer that something serious might have happened on her unit. Later, as police interviews spread anxiety among the staff, colleagues remembered both her resistance to the form and her friendship with Cullen; Loughren herself feared what the investigation might mean for her.

Saint Barnabas’s investigations closed in late December 1991 without a conclusion. Cullen was fired in the first week of January 1992, and the insulin spikes stopped. Saint Barnabas has maintained that the timing was unrelated and that the administration had no reason at the time to consider Cullen a risk to patients. Fragments of the inquiry were recovered only after his arrest. They included reports describing behavior that resembled the suspected method, but they did not settle what had happened in every case or establish what was in the unidentified IV bag.

Cullen’s employment records were also incomplete in a consequential way. Halfway through his five years at Saint Barnabas, he had joined Medical Center Health Care Services to gain greater flexibility over his hours and units. As a result, the hospital’s file covered only the final two years of his tenure. The investigation therefore ended with a stark contrast: the insulin episodes ceased when Cullen was dismissed, yet the hospital’s contemporaneous inquiry neither reached a conclusion nor accepted that the sequence established a connection.