(Reuters) – The billionaire founder of INSYS Therapeutics Inc John Kapoor, has resigned from the company’s board of directors, INSYS said in a statement on Sunday.

Kapoor was arrested on Thursday on U.S. charges he participated in a scheme to bribe doctors to prescribe a fentanyl-based cancer pain drug, marking a step by authorities to fight the opioid epidemic.

“I am confident that I have committed no crimes and believe I will be fully vindicated after trial,” Kapoor said in a statement on Sunday.

Kapoor, INSYS’ majority shareholder who stepped down as chief executive in January, said on Sunday that his continued involvement with INSYS would draw unnecessary attention to the company.

Kapoor was charged with engaging in conspiracies to commit racketeering, mail fraud and wire fraud in an indictment filed in federal court in Boston.

The charges marked a major escalation of investigations related to Subsys, an under-the-tongue spray that contains fentanyl, an addictive synthetic opioid. They came as U.S. President Donald Trump on Thursday declared the opioid crisis a public health emergency.

Kapoor was added as a defendant in a case against six former INSYS executives and managers, including former Chief Executive Michael Babich. Following a court hearing in Phoenix, Kapoor, 74, was released on a $1 million bond.