Manhattan federal prosecutors announced Wednesday that a doctor has pleaded guilty to illegally prescribing mass amounts of oxycodone, in a scheme that netted him more than $2 million in cash payments from patients at two clinics in Queens.

In a statement, prosecutors from the U.S. Attorney's Office for the Southern District of New York said that between 2011 and 2016, Emmanuel Lambrakis had written thousands of medically unnecessary prescriptions, resulting in the illegal distribution of more than 2 million tablets of oxycodone, a powerful and highly addictive narcotic opioid.

Lambrakis pleaded guilty Tuesday to one count of conspiring to unlawfully distribute and possess with intent to distribute oxycodone, which carries a maximum sentence of up to 20 years in prison.