NEW YORK -- A New York City doctor who wrote prescriptions for a man who killed four people in a pharmacy robbery was hit Thursday with manslaughter charges that accuse him of causing the overdose deaths of two patients. 

Dr. Stan Li already had been accused of prescribing prescription drugs to addicts.

Li prescribed more than 500 pills to a 21-year-old man in the five weeks leading up the discovery of his body in a parked car in Queens in 2010, authorities said.

The cause of death was acute intoxication caused by a combination of Xanax and oxycodone. 

'Do no harm'
Authorities said they believe it's the first time a physician has been charged in New York with manslaughter in an overdose death. 

"Dr. Li flouted the fundamental principle in medicine -- first, do no harm," Special Narcotics Prosecutor Bridget Brennan said in a statement announcing the indictment. 

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Li, of Hamilton, N.J., appeared in court Thursday.

The 58-year-old Li has previously pleaded not guilty to peddling prescriptions to addicts and drug dealers from a Queens weekend clinic where he saw as many as 120 patients a day, moonlighting from his full-time job as an anesthesiologist at a New Jersey hospital.

One of Li's patients, David Laffer, shot and killed two employees and two customers while holding up a Long Island pharmacy for painkillers in June 2011. Authorities have said that Li provided 24 prescriptions filled by Laffer.

Laffer is serving a life sentence for murder.

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