ST. PETER — A state investigation has resulted in fines against a hospital for violating rules in caring for mentally ill patients.

A yearlong investigation by the Human Services Department, which oversees the Minnesota Security Hospital, found staff repeatedly violated rules about patient care and in one case forced a patient to sleep on a concrete slab for 25 nights.

The hospital houses 220 of the state’s most dangerous mentally ill patients who have been civilly committed by a judge. Human Services Commissioner Lucinda Jesson says none of the employees accused of abuse have been fired. Jesson said that there needs to be more training and less restraint.

The hospital’s license has been placed on a conditional status for two years and a $2,200 fine was levied, the most allowed by law.