Colorado Revised Statutes Title 30. Government County § 30-10-716. Treasurer to assess property, when

It is the duty of the county treasurer to assess, at a fair value, the property of any person liable to pay taxes which the county assessor has failed to assess, to place the same on the tax roll, and to collect taxes on the same in the manner provided by law. Such treasurer shall not be compelled to assess such property in person; and he is authorized to administer oaths to such persons, or any others, touching the value of said property.