The CEO of drug giant Insys Therapeutics bribed doctors to prescribe more opioids to patients who didn’t even need them, according to federal authorities who arrested the executive after a raid on Thursday—a major offensive in the battle against America’s opioid epidemic.

John Kapoor, the billionaire founder and CEO, led “a nationwide conspiracy to profit by using bribes and fraud to cause the illegal distribution of a fentanyl spray intended for cancer patients experiencing breakthrough pain,” the Department of Justice said in a statement.

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