The investigation of Charles Cullen at Saint Luke’s Medical Center began not with a hospital referral to police but with a nurse who would not let her concern disappear into an internal review. Staff described patients declining and dying unexpectedly, sometimes after Cullen changed their IVs; records and drug evidence raised further questions. Yet months of scrutiny failed to turn a disturbing pattern into proof that could support a prosecution. The inquiry’s central contradiction endured: Cullen’s colleagues had reasons to suspect him, while the surviving paperwork left the deaths difficult to attribute to him with legal certainty.

Warning Signs and the First Report

Nurse Pat Medellin had seen unusual deaths on her unit and had also seen Cullen marched out of Saint Luke’s for diverting dangerous medications. She believed he was responsible for the deaths. When she pressed the hospital administration to act, the response was that Cullen had harmed no patients, and the hospital’s investigation was closed. The institutional conclusion did not settle the question for Medellin; it sharpened the divide between what staff suspected and what the hospital was prepared to acknowledge.

On August 29, 2002, Medellin took her account to an acquaintance who worked for the Easton, Pennsylvania, Police Department. From there, the report moved upward through police command, to the coroner, and on to the Lehigh County District Attorney’s Office. Pennsylvania State Police troopers then interviewed Saint Luke’s staff. The investigation was therefore set in motion by an individual nurse’s persistence, not by the hospital’s own escalation of its concerns.

The suspicions were grounded in a pattern of clinical events, but pattern alone could not establish who had caused them. Saint Luke’s staff described patients who seemed to be recovering and then suffered sudden, unexplained crises. Some remembered Cullen changing IVs shortly before a patient coded; others recalled him leaving a patient’s room shortly before a death. These accounts gave investigators a direction to pursue, but they remained observations and recollections rather than direct proof of what had entered a patient’s body.

Deaths, Drugs, and Witness Accounts

Nurse Lynn Tester noticed that patients who had been on the mend were dying suddenly and strangely, often after Cullen changed their IVs. Her comparison of his work hours with deaths on the unit made the discrepancy stark: Cullen worked about 26 percent of the hours but was present for 58 percent of the deaths. Another nurse recalled a change in the unit’s rhythm: while Cullen worked in the CCU, staff could see twenty to twenty-two Code Blues a month; after he left, the unit went six months without one. Neither comparison established that Cullen had caused any particular death, but together they made ordinary coincidence harder for staff to accept.

Robin Saulsberry described seeing Cullen slip out of a patient’s room shortly before that patient unexpectedly coded and died. She also remembered him watching the unit’s EKG monitor with such absorption that he did not look away while speaking. Saulsberry, who held a PhD in chemistry, believed the patient might have received Pronestyl, a drug Cullen had been discovered dumping from the medication closet shelves. Her interpretation connected an observed death, Cullen’s conduct, and a missing drug; it remained an informed suspicion, not a laboratory finding proving that he administered the drug to that patient.

The concern about medication access was not abstract. During one Saint Luke’s episode, a dangerous paralytic had apparently been reconstituted in syringes even though no patient on the CCU had been prescribed it during the four-shift weekend. Staff grew uneasy about who was entering the medical storage room and began taking turns watching it. Kim Wolfe saw Cullen arrive early, perform his customary rearrangement of chairs, and enter the locked room after punching in the code. The observation established that he had access to the room; it did not establish what he did inside. That distinction—between opportunity and proof—would shape the investigation.

The book also shows how a medication could be introduced without an overtly suspicious gesture. Cullen could inject digoxin through the piggyback port of an IV, an access point nurses routinely used to flush a line. He could present the action as ordinary care; the clear drug would not be visually distinguishable from saline. In another described sequence, he handled medicines alone in the supply room, prepared syringes, and returned them to named patient trays. These scenes clarify why suspicious access and drug diversion mattered to investigators, while not turning access itself into proof that he caused every death under review.

The Inquiry and Its Evidentiary Limits

The Pennsylvania State Police assembled a substantial investigation, with physical evidence, bodies, and dozens of cooperative witnesses. Their accounts were strikingly consistent about deaths on the night shift, and the pattern of codes appeared to change after Cullen left. But consistency among witnesses did not by itself identify a specific act, drug, or perpetrator in a specific death. Coroner Zachary Lysek worried that the number of deaths potentially attributable to Cullen might be fifty—or none. His uncertainty was not a lack of concern; it was recognition that suspicion could not substitute for scientific certainty.

The Lehigh County District Attorney’s Office retained Dr. Isidore Mihalakis, the pathologist who had also been involved in the investigation of Helen Dean’s suspicious death at Warren Hospital. Over several months, he reviewed charts for seventeen patients selected by Saint Luke’s. The paperwork yielded nothing prosecutable. The records could trace prescriptions, treatment, and decline, but the suspected drugs were not reliably documented as having been administered by Cullen. The investigation could not bridge the gap between an abnormal death and an individual criminal act using the charts alone.

Saint Luke’s personnel records offered a further contrast between what staff feared and what the institution recorded. The file described Cullen as a nurse who resigned after repeated reprimands; the status entry said he had resigned and should not be considered for rehire because of a medication issue. It did not name vecuronium bromide or the other powerful drugs associated with the suspicions. The absence of those details did not prove a deliberate cover-up: the hospital may not have had concrete evidence that Cullen intentionally overdosed a particular patient. Still, the restrained record left little for a later investigator to follow and, whether by design or accident, limited the paper trail beyond the hospital.

Closure and the Case’s Afterlife

When Tim Braun and Danny Baldwin later examined the Pennsylvania investigation, its closure was already a fact. The Lehigh County district attorney had ended the case five months before their own investigation began. Eight months of work had produced a formidable dossier but, from a prosecutorial standpoint, no case that could proceed. The most plausible explanation was evidentiary: prosecutors could not be confident they could prove either that a particular patient had been murdered or that Cullen had done it. Braun could imagine retracing the same path with fewer resources, fewer witnesses, and no guarantee of a different result.

That earlier failure changed the meaning of the material available to the later investigators. A cluster of deaths, access to dangerous drugs, and witnesses who associated Cullen with patients’ final crises could make him a strong suspect without supplying the decisive link needed in court. The investigation at Saint Luke’s thus ended not in exoneration or conviction but in unresolved suspicion. Its record showed both the force of cumulative warning signs and their limit: when hospital charts omitted the suspected drug and no direct evidence connected Cullen to a specific death, even an extensive inquiry could leave the central question unanswered.