Cook County Sheriff Tom Dart says people need to be held accountable for reported runaways at residential centers where wards of the state are housed.  He testified Wednesday at a legislator hearing in the wake of a newspaper investigation.  The Chicago Tribune has published a series looking into allegations of violence, assault and prostitution at some of the approximately 50 centers in Illinois.  The Tribune cites interviews and agency data.  The newspaper reported there were nearly 30,000 runaways between 2011 and 2013.  Dart says some runaways are lured into prostitution.  He says more money isn’t the answer and managers need do a better job.  Illinois Department of Children and Family Services Director Bobbie Gregg says abuse claims at centers are “appalling” and “unacceptable,” but have plagued child welfare for decades.