The OR assistant who saw a traveling nurse swipe fentanyl, then refill the empty syringe with water, didn't wear her glasses to his trial and couldn't point him out in the courtroom. Nevertheless, a panel of appeals court judges agreed that the other evidence presented at trial was sufficient to convict him.

In June 2007, during a contract assignment at Copley Hospital in Morrisville, Vt., traveling nurse James Erwin was charged with theft and possession of narcotics. The charges stemmed from a co-worker's report. An OR assistant referred to in court records as "D.B." said she'd seen him pocket something from an anesthesia cart between cases.

"She had noticed him spending a lot of time near this cart over the prior weeks," said the records, "and defendant had no job responsibility that would require him to be there." A few minutes later, she saw him at a scrub sink, filling a syringe with water.

D.B. reported the incident to the hospital's director of anesthesia, who determined that a syringe in the cart had been tampered with. When questioned, Erwin denied D.B.'s account. He was placed on administrative leave and a urine drug test detected the presence of fentanyl.

At the criminal trial, D.B could not identify Mr. Erwin during her testimony due to her missing eyeglasses. The anesthesia director and OR manager could, however, and prosecutors armed with laboratory reports secured a conviction.

Mr. Erwin appealed the conviction to Vermont's Supreme Court, citing the inability of the only eyewitness to a theft to see the thief in the courtroom, among other legal errors. In its April 26 ruling, though, the court rejected these claims, finding the prosecution's circumstantial evidence sound.

Representatives of the Vermont attorney general's office and the state defender general's office, who argued Mr. Erwin's appeal, did not immediately return calls seeking comment.

David Bernard