The coroner's expert at the inquiry into the death of Teresa Scheunert testified yesterday that the mixed effect of three drugs killed her, saying if she had been found in a back alley of Vancouver’s Downtown Eastside, “it would have been no surprise.”

But, later in the day, a second medical expert said it's impossible to know for sure what killed Scheunert.

A Coroner's inquest is being held in Whitehorse into Scheunert's death. The 47-year-old died in 2012 while being treated for back pain at the Watson Lake Hospital, where she worked as a nurse.

Dr. Thomas Perry is the pharmacology expert for the Yukon Hospital Corporation

He says he's still mystified why the Watson Lake nurse died when she did.

Perry testified, "as dangerous as they are, opiates are rarely the sole cause of death."

He told the jury it's easy to speculate her dosage was too high, but "it's not easy to kill someone with opiates alone."

Perry pointed to Scheunert's high tolerance for the drugs, and evidence she had additional narcotics in her possession when she started treatment at Watson Lake hospital.

Perry conceded, "mixed drug toxicity" is the most obvious conclusion to reach, but insisted more effective monitoring of the patient was required to know for sure.

Jurors were told yesterday that reports on what caused Scheunert’s death are speculative.

Today, they’ll hear from a narcotics safe practices expert.