Lynn Tester

Lynn Tester was a nurse at Saint Luke’s whose observations helped turn suspicion about Charles Cullen into a measurable pattern. She noticed patients who seemed to be recovering die suddenly, often soon after Cullen changed their IVs; when she compared his time on the unit with its deaths, she found that his share of the deaths far exceeded his share of the hours worked. Her account supplied investigators with a pointed pattern, not proof of responsibility for any individual patient’s death.

Identity and Observations

Tester worked on the Saint Luke’s CCU. She described patients as “people on the mend” who died unexpectedly, and noticed that the deaths followed changes Cullen made to their IVs. The timing stood out against the patients’ apparent improvement: these were not simply cases she understood as a steady decline, but abrupt deaths occurring after Cullen’s contact with their lines.

The Pattern in the Numbers

Tester calculated that Cullen worked only 26 percent of the hours but was present for 58 percent of the deaths. The comparison gave numerical form to what she and other nurses had noticed at the bedside. It did not, on its own, establish what Cullen had done to a specific patient; it made the concentration of deaths during his shifts harder to dismiss as an impression alone.

Investigative Significance and Limits

Tester's observations were among accounts from Saint Luke’s staff that pointed to unusual deaths on the night shift and to Cullen’s proximity to patients before they coded. Another nurse recalled that the unit had averaged twenty to twenty-two Code Blues a month while Cullen worked there, then went six months without one after he left. That was a separate nurse’s observation, but it reinforced the contrast surrounding Tester’s account.

The pattern prompted scrutiny, but the medical records did not yield a prosecutable case. An outside pathologist reviewed charts for seventeen patients selected by Saint Luke’s and found nothing prosecutable in the paperwork. Tester’s figures therefore remained significant as a warning and a lead for investigators, while the evidence available in the charts fell short of proving that Cullen had caused particular deaths.