March 4, 2012 -- A doctor in Los Angeles County has been charged with murder after three of her patients died of prescription drug overdoses.

Dr. Hsiu-Ying "Lisa" Tseng, 42, an osteopathic physician in Rowland Heights, Calif., allegedly wrote an average of 25 prescriptions per day over the last three years for addictive painkillers such as Oxycontin and Vicodin, with little regard for her patients' medical histories, according to ABC station KABC-TV in Los Angeles.

It's rare that a physician is charged with murder when a patient dies in connection with his or her treatment, according to James Acker, a professor at the School of Criminal Justice at the University of Albany, SUNY.

"Far more typically, although still unusual, is to charge a physician with criminal homicide," a lesser charge, he said.

For example, Dr. Conrad Murray was convicted of involuntary manslaughter for the death of his patient, the singer Michael Jackson.

More than 200 physicians have been arrested or convicted in connection with patients' prescription drug overdoses since 2003, according to the Drug Enforcement Agency.

"Where you are knowingly engaging in risky behavior, and it's likely that an adverse consequence such as a death will result, that's sufficient to consider it homicide," said Acker, who is not connected with the case.

Tseng was arrested Thursday and charged with murder in the deaths of Vu Nguyen, 29, of Lake Forest, on March 2, 2009; Steven Ogle, 25, of Palm Desert, on April 9, 2009; and Joseph Rovero III, 21, an Arizona State University student from San Ramon, on Dec. 18, 2009, KABC-TV reported.

Prescription painkiller overdoses killed nearly 15,000 people in the United States in 2008, three times as many people as were killed by painkiller overdoses in 1999, according to a report from the Centers for Disease Control.

Many young people believe that prescription drugs are "much safer" than illegal drugs, according to the Drug Enforcement Administration.

In fact, some 7 million Americans aged 12 years and older reported in 2009 that they'd abused prescription drugs for non-medical purposes within the past month, a 13 percent increase from the 6.2 million who did so in 2008, according to the DEA.

Los Angeles District Attorney Steve Cooley told KABC-TV that Tseng was prescribing medication that "was probably not needed at all, to feed someone's habit."

Undercover officers from the Drug Enforcement Administration had been posing as patients and investigating her practice for the last few years, while she was writing some 27,000 prescriptions starting in Jan. 2007, reported KABC-TV.

KABC-TV said the DEA suspended Dr. Tseng's license to write prescriptions in 2010, and she eventually surrendered her license to the Osteopathic Medical Board of California's Department of Consumer Affairs.

She is being held on $3 million bail and is scheduled to be arraigned on March 9, when she'll face some 21 other felony counts, including alleged fraud for prescribing drugs without a legitimate purpose, KABC-TV said.

Her husband, also a doctor, continues to run her clinic in Rowland Hills, reported KABC-TV. An assistant who answered the phone at the clinic said that Tseng's husband was not there and would not respond to ABCNews.com's request for comment.

Tseng's attorney, Peter Osinoff of the firm Bonne, Bridges, Mueller, O'Keefe & Nichols, did not immediately respond to a request for comment.

One mother, Jodi Barber, 52, of Laguna Niguel, Calif., said she knows all too well the tolls that prescription drug abuse can take on young lives.

After her 19-year-old son died of a prescription drug overdose in January 2010, she co-created documentary called "Overtaken" to shed light on the problem.

Barber said she was unaware of her son's short battle with painkillers until three months before his death. She said that one of her son's friend's gave him just a quarter of a pill, which they'd crush and snort, and which was enough to get him hooked.

Barber alleges that another friend of her son's who went to Tseng for drugs then sold them to her son; that boy died five months later, she said.

"These kids would go to her, and she'd give them 90 Opana [oxymorphone, a narcotic used to treat moderate to severe pain]," Barber said.

She said she partially blames Tseng for her son's death.

"She's the professional, and she knows better," Barber said. "She overprescribed, and she prescribed deadly combinations."