Transcript for California Doctor on Trial After 3 of Her Patients Overdose on Painkillers
Right to you to that landmark case in California where a doctor is on trial for murder accused of killing three patients who overdosed on powerful painkillers she prescribed. Mara schiavocampo has the story. Reporter: Officials say Dr. Tseng was aware her patients were misusing those prescriptions one even overdosing in her office and several dying. Now she's facing criminal charges in a case that could change the way doctors all over the country handle prescriptions. She's the doctor accused of killing patients with prescriptions. The defendant repeatedly had patients overdose and die. Reporter: This morning, Dr. Lisa Tseng facing second degree murder charges for the deaths of three patients, all in their 20s who allegedly overdosed on drugs she prescribed. In opening statements, prosecutors saying even though Dr. Tseng was informed more than a dozen times her patients were overdosing, she kept prescribing powerful painkillers like oxycontin to the point of recklessness but the defense says Dr. Tseng is not guilty, that she's a hard working mother who never meant to hurt anyone. Adding the victims are ultimately responsible for taking more than the prescribed dosage and mixing pills with alcohol. She wasn't a perfect doctor, but these patients took a lot into their own hands. They mixed alcohol. They mixed other drugs. Reporter: Three pharmacists taking the stand Tuesday all three testifying the prescriptions written by Dr. Tseng and the patients filling those prescriptions raised red flags. The quantities were large. And that person would seem intoxicated or seem under the influence of drugs. Reporter: Though rare more doctors are facing these kinds of charges. In 2011 Dr. Conrad Murray was convicted of involuntary manslaughter for giving Michael Jackson a deadly dose of the anesthetic propose follow. Now some legal experts say cases like Tseng's could set a new deflated footballs this set for
This transcript has been automatically generated and may not be 100% accurate.