MAPLE LAKE (AP) -- State investigators have concluded that three teenage boys at a Wright County residential treatment center were sexually abused by a female staff member in March.

The worker at Maple Lake Recovery Center also exchanged personal contact information with the boys via social media.

The staff member was not identified in the Department of Human Services report. She has resigned and is barred from having contact with people receiving social services through state-licensed programs.

It's the second time in less than three years that state investigators have substantiated sexual abuse at the addiction treatment center.

The state report says the facility has provided additional training to staff on appropriate behavior with patients. Facility and state officials declined comment on whether the March incident has been referred to law enforcement.