Colo. Rev. Stat. § 16-7-102
If the defendant intends to introduce evidence that the defendant was at a place other than the location of the offense, the defendant shall serve upon the prosecuting attorney as soon as practicable, but not later than thirty-five days before trial, a statement in writing specifying the place where the defendant claims to have been and the names and addresses of the witnesses the defendant will call to support the defense of alibi. Upon receiving the defendant's statement, the prosecuting attorney shall advise the defendant of the names and addresses of any additional witnesses who may be called to refute such alibi as soon as practicable after the names of such witnesses become known. Neither the prosecuting attorney nor the defendant shall be permitted at the trial to introduce evidence inconsistent with the specification statement unless the court for good cause and upon just terms permits the specification statement to be amended. If the defendant fails to make the specification required by this section, the court shall exclude evidence offered in support of the defense of alibi unless the court finds upon good cause shown that such evidence should be admitted in the interest of justice.
C.R.S. § 16-7-102