A former nurse in Texas is set to be sentenced for the deaths of four patients who prosecutors said died after he injected them with air following heart surgeries.

The Smith County jury in Tyler took only an hour to declare William George Davis guilty of capital murder involving multiple victims. Sentencing is scheduled to begin Wednesday. Prosecutors said they will seek the death penalty, reported the Tyler Morning Telegraph.

Davis, 37, was charged with injecting air into the arteries of four patients after they underwent heart surgery at the Christus Trinity Mother Frances Hospital in Tyler in 2017 and 2018. John Lafferty, Ronald Clark, Christopher Greenway and Joseph Kalina all experienced neurological issues during recovery and died.

Following an investigation, Davis was fired from the hospital in February 2018 for falsifying care events and unethical practice related to failure to disclose interventions provided that may have affected patient outcomes. After his dismissal, the incidents of air in the brain and damage stopped, said the prosecution.

Defense attorney Philip Hayes accused the hospital of using Davis as a scapegoat to cover up its problems and because Davis was there when the deaths occurred. He said that the patients who died showed a classic pattern of watershed strokes and had prior health issues that could have led to complications and death. “At least two of those individuals that passed away Will was trying to administer lifesaving drugs to, or process to,” he said, according to ABC News-affiliate, KLTV.

Dr. John Schnell, former Christus Mother Frances chief of emergency medicine and the defense’s expert witness, told the jury that it was anatomically impossible for air to go against blood flow. But Dr. William Yarbrough, a pulmonologist and professor of internal medicine from Dallas, said he was able to determine from brain scans that air was injected into the arterial system of each patient’s brain and explained how air injected into the arterial system can cause brain injury and death.

Security footage in court also showed that Davis was the last person to enter Kalina’s room. Davis said he went in to silence an IV pump. Records later showed an alarm was not going off. And despite telling the hospital that he responded immediately to help Kalina, the video showed his response was slower.

Prosecutor Chris Gatewood said that Davis did not tell the other nurses what happened and stood by as others responded to help Kalina. Scans later showed air in the brain, with Kalina dying two years after from brain damage.

Gatewood said similar incidents were found with Lafferty, Clark and Greenwood and dismissed the suggestion of stroke-like events as “red herrings” and attempts to misdirect the jury. He said that Davis lied about why he was in the rooms of each patient and was the only nurse on the floor at the time that each one experienced complications. He told the jury that Davis “liked to kill people,” while Smith County District Attorney Jacob Putman maintained that the hospital did not change any of its procedures, according to KLTV. “With the facts that we have, with the evidence that we have, a serial killer being in the hospital is the only thing that makes sense,” said Gatewood.

Hayes accused one of the state witnesses, Teresa Meeks, clinical director at cardiovascular ICU, of misleading the jury and trying to hide evidence related to the timeline of Kalina’s neurological event.

Davis’ nursing license was suspended in March 2018, and he was arrested that April on bonds totaling $8.75 million and indicted on charges of capital murder, murder and five counts of aggravated assault with a deadly weapon. He initially pleaded not guilty when the trial began in September but opted not to take the stand Monday. His wife and two children were present at the trial.

While Hayes acknowledged that Davis lied to hospital executives about events, he refuted the suggestion that Davis murdered any patients. “If they want to charge him with being dishonest, okay, we’ll deal with that issue. But being dishonest does not make you a murderer, it does not make you a killer or a serial killer.”

The jury will hear more testimony at sentencing and decide between giving Davis life in prison or the death penalty.