New charges have been filed against a Merrick doctor already accused of handing out illicit prescriptions for a powerful painkiller.

Dr. Michael Belfiore was first arrested in October 2014. Federal prosecutors said he illegally wrote thousands of prescriptions for the highly addictive oxycodone to patients who did not medically need it. In Central Islip court Tuesday, prosecutors said two of those patients died after overdosing on pills they got from prescriptions filled out by Belfiore.

According to the 29-count indictment, Belfiore wrote 5,000 prescriptions for more than 600,000 oxycodone pills in a three-year period, which federal prosecutors said is highly unusual.

Belfiore's attorney disagrees, saying that number is reasonable considering the number of patients seen by his client.

The doctor told News 12 that his Merrick practice is still open.

Belfiore is due back in court at the end of next month. If convicted, he faces 20 years in prison and a $1 million fine.