A doctor named in the ongoing nationwide fraud investigation of Phoenix-based Insys Therapeutics was sentenced on Monday to 32 months in prison.

Gavin Awerbuch admitted to writing prescriptions for Insys' fentanyl-based cancer pain medication Subsys for non-legitimate uses and committed health care fraud.

In addition to prison, Awerbuch must also pay $4.1 million in restitution and fines.

Prosecutors say he was once the largest prescriber nationally of Subsys to people covered by Medicare.

Awerbuch, other doctors and former company execs were indicted by federal prosecutors as part of the investigation.

Prosecutors have accused founder John Kapoor and other ex-Insys executives of conspiring to bribe doctors to prescribe Subsys.

Insys has said it may need to pay at least $150 million to resolve the U.S. Justice Department's investigation.