PHOENIX (AP) - U.S. authorities say the founder of an Arizona-based pharmaceutical company has been arrested and charged with leading a nationwide conspiracy to bribe doctors to prescribe a powerful opioid pain medication.

The U.S. Attorney's Office for Massachusetts said Wednesday that John Kapoor of Insys Therapeutics Inc. and former executives and managers are charged with racketeering and other crimes in a new indictment.

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Amid a national opioid addiction crisis, Kapoor of Phoenix and the other defendants are accused of offering kickbacks to doctors to write large numbers of prescriptions for a fentanyl-based pain medication that's meant for cancer patients. Most of those who received the prescriptions weren't cancer patients.

Kapoor is to appear Thursday in federal court in Phoenix.

The indictment adds new allegations to an ongoing case. The former executives and managers have pleaded not guilty.

READ: Arizona doctor indicted for forging opioid prescriptions