A jury found a Texas nurse guilty of capital murder of four patients after prosecutors asserted the nurse injected the patients with air while recovering from heart surgeries.

37-year-old William George Davis was convicted of capital murder on October 19 for murdering four patients after a Smith County jury returned a guilty verdict after roughly one hour of deliberation, according to the Associated Press.   

“The jury would not have returned the verdict that quickly if they thought the district attorney’s office had been in a rush, or sloppy, or somehow not up to standards when they presented the case,” East Texas attorney Randy Roberts said in an interview with KETK.

Davis stood trial for the murders of John Lafferty, Ronald Clark, Christopher Greenway, and Joseph Kalina, after they all endured unexplained neurological complications and perished after receiving heart surgery at Christus Trinity Mother Frances Hospital in Tyler, Texas, the Associated Press reports. The deaths of the four men took place in 2017 and 2018. 

Dr. William Yarbrough is a pulmonologist and professor in the Dallas area and informed the jury of how a person can suffer brain injury or death when the arterial system of the brain is injected with air, the Associated Press reported. After observing brain scans of the victims he found air in the arterial systems of the brains, which he says he has never witnessed in decades of practicing medicine, according to the Associated Press. 

Yarbrough was able to rule out blood pressure complications and other causes of death and asserted that the difficulties came after surgery as the patients were in recovery, the Associated Press reported. 

The second phase of the trial began on October 20, where it will be decided if Davis should receive the death penalty or life in prison without parole, according to KETK. 

On the first day of phase two, Jacob Putman, Smith County’s district attorney, said the prosecution will prove Davis murdered three additional patients and attempted to murder five others, bringing the total number of victims to twelve, according to CBS 19.

Putman was able to introduce the additional victims as both the prosecution and defense are attributed broader discretion to present mitigating and aggravating evidence to determine if Davis would pose a threat to others if he were to be imprisoned, according to KETK.

The Case is The State of Texas v. Davis No. 114-0835-18 in District Court of Smith County, Texas.