The Department shall conduct an investigation to ascertain the facts relating to the violations alleged in the complaint and determine whether a violation under the Act has occurred. The investigation may be made by written or oral inquiry, field visit, conference or any method or combination of methods deemed suitable at the discretion of the Department. The Department shall notify the contractor in writing, within 120 days after the filing of a complaint, of the filing of a complaint and provide the employer the locations of the projects, approximate dates of the projects, affected contractors and the nature of the allegations being investigated. The Department shall provide the contractor an opportunity to present any information the contractor wishes the Department to consider in reaching its determination.
Ill. Admin. Code tit. 56, § 240.300