Colorado Code
Article 50 - Joint Rights and Obligations
§ 13-50-103. Liability of Remaining Debtor

In case one or more joint debtors are released, no one of the remaining debtors shall be liable for more than his proportionate share of the indebtedness, unless he is the principal debtor and the debtor released was his surety, in which case the principal debtor is liable for the whole of the remainder of the indebtedness.
Source: L. 1899: p. 239, § 2. R.S. 08: § 3606. C.L. § 5126. CSA: C. 92, § 6. CRS 53: § 76-1-3. C.R.S. 1963: § 76-1-3.