Retaliation prohibited.

An employer may not discriminate in any manner or take adverse action against any person because the person: Makes an oral or written complaint with the employer or the Mayor alleging that the employer violated any provision of this subchapter or any rule issue pursuant to this subchapter; Brings an action or initiates a proceeding involving a violation of this subchapter; Testifies in an action authorized under this subchapter or a proceeding involving a violation of the provisions of this subchapter or any rule issued pursuant to this subchapter; or Assists in an investigation by providing information to a litigant in a civil action, the Mayor, or another agency in proceedings as provided by [this] subchapter. A person who believes that an employer has discriminated in any manner or taken adverse action against the person in violation of this subchapter may submit to the Mayor a written complaint, signed by the complainant, that alleges the discrimination. Upon receipt of a complaint, the Mayor shall conduct an investigation.