Texas nurse convicted of killing 4 men with air injections

A Texas nurse was convicted Tuesday of capital murder in the deaths of four patients who died after prosecutors say he injected them with air following heart surgeries.

The Smith County jury deliberated for about an hour before finding William George Davis, of Hallsville, guilty of capital murder involving multiple victims. Prosecutors planned to seek the death penalty during the sentencing phase, which was scheduled to start Wednesday.

Davis, 37, was accused of injecting air into the four patients' arteries after they underwent heart surgery at the Christus Trinity Mother Frances Hospital in Tyler in 2017 and 2018. During recovery from their surgeries, the four -- John Lafferty, Ronald Clark, Christopher Greenway and Joseph Kalina -- suffered unexplained neurological problems and died.

During the trial, Dr. William Yarbrough, a Dallas-area pulmonologist and professor of internal medicine, explained to the jury how injecting air into the arterial system of the brain causes brain injury and death.

Yarbrough said he was able to determine there was air in the arterial system of the victims' brains by viewing images from brain scans -- something he said he had never before observed in his decades in medicine.