405 ILCS 10/2
The terms "flight" and "fled" as used in this act, shall be construed to mean any voluntary or involuntary departure from the jurisdiction of the court where the proceedings hereinafter mentioned may have been instituted and are still pending, with the effect of avoiding, impeding or delaying the action of the court in which such proceedings may have been instituted or be pending, or any such departure from the state where the person demanded then was, if he then was under detention by law as a person of unsound mind and subject to detention. The word "state" wherever used in this act shall include states, territories, districts and insular and other possessions of the United States. As applied to a request to return any person within the purview of this act to or from the District of Columbia, the words "executive authority," "Governor" and "Chief Magistrate" respectively shall include a justice of the Supreme Court of the District of Columbia and other authority.
405 ILCS 10/2