Was the hepatitis C outbreak that infected more than 100 patients of Las Vegas-area endoscopy centers caused by the misuse of medication vials or dirty instruments and supplies? That question and more surrounding the evidence of what exactly went on at the clinics owned by former gastroenterologist Dipak Desai brought both civil and criminal trials surrounding the case to a halt this week.

On Monday, District Judge Donald Mosley ordered a yearlong delay in the criminal trial of Mr. Desai and 2 nurse anesthetists to give both prosecutors and defense attorneys more time to sift through hundreds of thousands of pages detailing the findings of the Southern Nevada Health District's outbreak investigation.

Meanwhile, the Nevada Supreme Court began pretrial hearings to determine who can testify and what kinds of evidence can be presented in civil litigation against the clinicians and pharmaceutical companies involved. Last year, a lower court found 3 pharmaceutical firms liable of selling multi-use propofol vials, the misuse of which are believed to have contributed to the outbreak, and ordered the companies to pay more than $500 million in just one of the many civil lawsuits filed by outbreak victims.

In an appeal filed last week, attorneys representing the companies say they want jurors to hear testimony from nurses about other potential causes of the outbreak besides the reuse of propofol vials on multiple patients.

Although most experts believe unsafe infection practices were the primary cause of the outbreak, investigators also found problems with how medical equipment at the facilities was used and reprocessed, which defense attorneys argue may be the real culprit, reports the Las Vegas Review Journal.

Robert Eglet, the plaintiff's attorney who won the $505 million verdict against the pharmaceutical companies last year, argued on Monday that nurses shouldn't be allowed to take the stand and speak as experts on what may have caused the outbreak. "No appellate court at any level in the United States has ever permitted a nurse to give expert testimony," he argued before the Nevada Supreme Court.

Because there are several civil trials going on at once and the lower courts have ruled differently on which types of evidence and expert witnesses are permissible, those cases have come to a halt until the higher court renders a ruling.

Irene Tsikitas