Colo. Rev. Stat. § 16-18-104
If any person complains to any grand jury of injury done to his person, or to any person of his household, or to his property, and after indictment found does not appear in the court in which the indictment is pending to give evidence in that behalf against the party charged in the indictment, and the party charged is acquitted, or if proceedings under said indictment are discontinued for want of testimony, the court in which the indictment is pending shall give judgment against the person who preferred the complaint for the costs arising in that case. Upon the trial of the party charged in any such indictment, if he is acquitted and the jury finds that the proceeding was maliciously commenced, the court shall give judgment against the prosecuting witness for the costs arising in the case. Whenever any person complains, the grand jury shall cause the name of the person so complaining to be endorsed upon the indictment, with the words "prosecuting witness" added, and this shall be evidence that the complaint was made by the person whose name is thus endorsed.
C.R.S. § 16-18-104