A Santa Rosa neurosurgeon whose specialty includes pain management has been indicted by a federal grand jury on charges that include unlawful distribution of painkillers over more than a year.

The indictment against Thomas M. Keller, 71, unsealed Monday, alleges he illegally distributed Oxycodone, fentanyl and Tramadol spanning a period of 13 months from June 2017 to July 2018, according to the U.S. Attorney’s Office in San Francisco.

Keller gave the drugs to people as a licensed doctor but acting outside the scope of his practice and without a legitimate medical need, federal prosecutors contend.

Keller also faces two counts of health care fraud stemming from allegations that he submitted two fraudulent claims to insurers Anthem Blue Cross of California in March 2018 and to Medi-Cal in July 2015, the U.S. Attorney’s Office said in its written statement Tuesday.

Keller, a former U.S. Army and Air Force neurosurgeon who has practiced in Santa Rosa since 2008, said he learned of the charges in a San Francisco courtroom on Monday and has since suspended his practice. He said he could not comment on the case and referred questions to his attorney. She could not be immediately reached for comment Tuesday night.

The indictment stems from investigations conducted by the Drug Enforcement Agency, the FBI, the U.S. Department of Health and Human Services and the state Department of Justice.

If convicted of all charges, Keller faces a maximum sentence of 45 years in prison and fines up to $1.5 million. His next court appearance is set for Oct. 16.