BOSTON (Reuters) - A Rhode Island doctor pleaded guilty on Wednesday to charges he participated in a scheme to obtain kickbacks in exchange for writing prescriptions for an addictive fentanyl-based cancer pain drug produced by Insys Therapeutics Inc.

FILE PHOTO: A box of the Fentanyl-based drug Subsys, made by Insys Therapeutics Inc, is seen in an undated photograph provided by the U.S. Attorney's Office for the Southern District of Alabama. U.S. Attorney's Office for the Southern District of Alabama/Handout via REUTERS

The plea by Jerrold Rosenberg came amid ongoing investigations of Insys related to Subsys, an under-the-tongue spray that contains fentanyl, a synthetic opioid.

Rosenberg, 63, pleaded guilty in federal court in Providence, Rhode Island, to charges that he committed healthcare fraud and conspired to receive kickbacks to prescribe Subsys.

Prosecutors said that from 2012 to 2015, Rosenberg schemed to receive $188,000 in kickbacks in the form of speaker fees from Insys, which were a major factor in his decision to prescribe Subsys to patients.

He also fraudulently indicated that his patients suffered from cancer pain when they did not in order to secure insurance approvals for Subsys, prosecutors said.

Under a plea agreement, Rosenberg agreed to pay $754,736 in restitution to healthcare benefit programs. He faces a maximum prison sentence of 15 years and is scheduled to be sentenced on Jan. 16.

Rosenberg’s lawyer did not respond to a request for comment. Chandler, Arizona-based Insys in a statement said it has “taken necessary and appropriate steps to prevent past mistakes from happening in the future.”

The investigations into Insys have come during a national epidemic of opioid abuse. According to the U.S. Centers for Disease Control and Prevention, opioids were involved in more than 33,000 deaths in 2015. The death rate has continued to rise, according to estimates.

In December, federal prosecutors in Boston charged six former Insys executives and managers, including ex-Chief Executive Michael Babich, with engaging in a scheme to bribe doctors to prescribe Subsys and defraud insurers.

All six have pleaded not guilty. Federal charges have also been filed in several other states against other ex-Insys employees and medical practitioners who prescribed Subsys.

Insys has been in settlement talks with the U.S. Justice Department. It said on Wednesday it is working “with relevant authorities to resolve issues related to the misdeeds of former employees.”

Insys also faces lawsuits by attorneys general in Arizona and New Jersey. It previously paid $9.45 million to resolve investigations by attorneys general in Oregon, New Hampshire, Illinois and Massachusetts.

The case is U.S. v. Rosenberg, U.S. District Court, District of Rhode Island, No. 17-cr-00009.