C.R.S. § 18-5-305

(1) A person commits the crime of altering identification number if, with intent that identification of an article be hindered or prevented, he obscures an identification number or in the course of business he sells, offers for sale, leases, or otherwise disposes of an article knowing that an identification number thereon is obscured. (2) “Identification number” means a serial or motor number placed by the manufacturer upon an article as a permanent individual identifying mark. (3) “Obscure” means to destroy, remove, alter, conceal, or deface so as to render illegible by ordinary means of inspection. (4) Possession of an article on which an identification number is obscured is prima facie evidence that the person possessing it obscured the number with intent to hinder or prevent identification of the article, and that he knows that the identification number is obscured, unless, prior to his arrest or the issuance of a warrant for a search of the premises where the article is kept, whichever is earlier, he reports possession of the article to the police or other appropriate law enforcement agency. (5) Altering identification number is a class 2 misdemeanor.