Colo. Rev. Stat. § 31-10-809
After the polls have been closed, the election judges shall secure the vote recorders or the voting devices, or both the vote recorders and the voting devices, against further use and prepare a ballot return in duplicate showing the number of voters as indicated by the pollbook who have voted in the precinct, the number of official ballot cards received, and the number of spoiled and unused ballot cards returned. The original copy of said ballot return shall be deposited in a metal or durable plastic transfer box, along with all voted and spoiled ballots. The transfer box shall then be sealed in such a way as to prevent tampering with the box or its contents. The clerk shall provide such a numbered seal. The duplicate copy of said ballot return shall be mailed at the nearest post office or post box to the clerk by a judge other than the one who delivers the transfer box to the counting center. One judge shall deliver the sealed transfer box to the counting center or other place designated by the clerk.
C.R.S. § 31-10-809