BOSTON (AP) — The former chief executive of a company that produces a potentially addictive fentanyl spray has admitted to participating in a scheme to bribe doctors into increasing prescriptions to boost sales.

Former Insys Therapeutics CEO Michael Babich (BAH’-bich) pleaded guilty to conspiracy and mail fraud Wednesday in federal court in Boston.

Babich has agreed to cooperate with prosecutors and is expected to testify against the Chandler, Arizona-based company’s wealthy founder, John Kapoor, when he and other executives go on trial this month.

They are accused of scheming to pay doctors kickbacks in the form of speaking fees to get them to prescribe the powerful opioid painkiller to more people and in higher doses.

Former sales executive Alec Burlakoff pleaded guilty in November and is also cooperating with prosecutors. The trial begins Jan. 28.