PORTLAND -- Umatilla County prosecutors are considering criminal charges in the possible misuse of public money for food services at the Two Rivers Correctional Institution in Umatilla, the second time in recent years that the state's food services operation has been investigated for possible wrongdoing.

Food services manager Mike W. Mathisen, who was on paid leave during an investigation and resigned in November, said he did not misuse money and provided documents for the investigation.

He told The Oregonian that "after five months of waiting for the investigation to be completed, I decided to resign and pursue other things."

The 44-year-old managed the prison's central kitchen, overseeing about 100 inmates a day who worked to feed the prison population of 1,580. At the same time he was paid $59,000 for the state job, Mathisen ran catering and food-packing businesses in Hermiston, and established two local farmers markets.

Mathisen's supervisor was put on paid leave in November and returned to work last week, taking a demotion to counselor.

County District Attorney Dan Primus wouldn't discuss the reports but confirmed this week that he is weighing criminal charges. Corrections officials said they alerted state police to their investigation in late May.

If substantiated, the case would be the second time in recent years that Oregon prison officials have confronted corruption in the food services operation.

Mathisen stepped into the state's political spotlight two years ago, when conservative Republicans backed him in a bid to unseat state Rep. Bob Jenson, R-Pendleton. Mathisen lost the House primary.

The Corrections Department hired Mathisen in 2007, assigning him to food services at the Oregon State Penitentiary in Salem. The following year, he was promoted to the Umatilla prison.