Police arrested Hector Castro of the Itzamna Medical Center in Manhattan on charges of running an oxycodone-trafficking ring with activity in several states.

The investigation started over a year ago when a man in Middlesex, N.J., overdosed on the drug. A pill bottle was found on the scene with Castro's name on it, according to authorities.

Officials state that at least 500,000 pills were prescribed by Castro, according to the Wall Street Journal. However, due to laws in place the New York health department cannot track prescriptions that are filled outside the state.

This, says Special Narcotics Prosecutor Bridget Brennan, is a problem.

"A scheme to obtain prescriptions in one state, and fill them and distribute them in another, exposes weakness in our regulatory systems," she stated in a release.

Authorities believe prescriptions issued from Castro's office were filled in New York, New Jersey and Pennsylvania over a period of two years.

In all, 43 people have been arrested in Pennsylvania alone in what has quickly become the state's biggest mass arrest related to prescription drugs yet. In addition to the arrests, 30 guns were confiscated in a series of stings that took place in New York and Pennsylvania. 

Authorities do not believe Castro is the only one behind the prescriptions, however. Patricia Valera, Castro's office manager, is believed to have ran a separate scheme of forging stolen prescription sheets that she later sold to drug trafficking rings in Pennsylvania.

Both have pleaded not guilty and are being held until their hearings on April 11.