Law Office of Riley N. Oncken Attorneys Law Office of Riley N. Oncken Visit Website 212 South Main Street Sycamore, IL 60178 (815) 991-2098 (815) 991-2128 (fax) Facebook About About Riley N. Oncken is an experienced litigator and prefers to spend his days in the courtroom, rather than the office. Riley handles matters in most counties in Northern Illinois.