BILLINGS, Mont. (AP) — A former office coordinator at St. Vincent Healthcare in Billings has pleaded guilty to embezzling more than $55,000 from the hospital over a three-year period.

The Billings Gazette reports Karen Kay Nieder pleaded guilty to theft by embezzlement Thursday in District Court. The plea agreement calls for Nieder to be sentenced to 10 years in prison with all but 30 days suspended, along with fines and restitution.

Nieder admitted taking the money between September 2007 and May 2010.

Prosecutors say Nieder used a "quasi-Ponzi scheme" to cover her thefts by crediting past-due accounts with payments from other clients.

Nieder began working at the hospital in 1979. She was fired after the thefts were uncovered.