LOS ANGELES (CBS) — April Rovero wants to know how her son’s doctor sleeps at night.

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She lost her youngest, Joey, two years ago.

Joey Rover, at the time a student at Arizona State University, overdosed on a combination of prescription drugs. These were drugs prescribed by Dr. Hsui-Ying “Lisa” Tseng, a doctor who was recently arrested and accused of being a Dr. Feelgood, someone who over-prescribed, no questions asked.

Dr. Tseng — a 42-year-old Rowland Heights osteopathic physician —  is accused of being responsible for the deaths of three young men, all in their 20s, otherwise healthy, according to prosecutors.

April Rovero doesn’t know how this could have happened. “It just chills me. I do not know how she can sleep at night.”

Hsiu-Ying “Lisa” Tseng, 42, was arrested Thursday by state Medical Board investigators. (credit: LA Times)

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Dr. Tseng was charged today with second-degree murder. She was also charged with 20 felony counts of prescribing prescription medication without a legitimate purpose and fraud.

Joey Rovero’s mother was in court when a tearful Tseng, also a mother, pleaded not guilty.

April Rovero dismissed the doctor’s tears. “I felt no sympathy for her. As many tears as I have for my son.”

Rovero insists her son was healthy. She says she found out he paid cash and was prescribed large amounts of Oxycodone, Xanax, and Alprazolam and sent to a pharmacy a half-hour away.

Joey Rovero died nine days later — a combination of the pills and alcohol in his system. His mother says her son can’t die in vain. “Justice has to be served or it will be open season on this kind of behavior.”

In America, every 19 seconds, Joey’s mother says someone else dies of a prescription drug overdose. “That is horrifying to me.”

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In honor of her son, she now runs the National Coalition Against Prescription Drug Abuse. For more about the organization, click here.