GREAT FALLS, Mont. — A former Great Falls chiropractor who pleaded guilty to sexually assaulting an employee has been sentenced to 5 years in prison.

The Great Falls Tribune reports ( ) District Judge Dirk Sandefur sentenced 48-year-old Reese Riggin on Thursday after expressing frustration with the binding plea agreement that he felt was too lenient.

The Montana Board of Chiropractors revoked Riggin’s license two years ago after former employees reported he touched them inappropriately during adjustments he required under the terms of their employment.

He was charged in October 2014 and pleaded guilty in March to sexual intercourse without consent. The agreement called for a 20-year sentence with 15 suspended.

Riggin lost his chiropractic license in Idaho over similar allegations in 1997. He pleaded guilty to misdemeanor sexual exploitation by a medical care provider.

Information from: Great Falls Tribune,