The branching ratios for the spin-forbidden photodissociation channels of (CO)-C-12-O-16 in the vacuum ultraviolet (VUV) photon energy region from 102 500 (12.709 eV) to 106 300 cm(-1) (13.180 eV) have been investigated using the VUV laser time-slice velocity-map imaging photoion technique. The excitations to three (1)Sigma(+) and six (1)Pi Rydberg-type states, including the progression of W(3s sigma) (1)Pi(nu' = 0, 1, and 2) vibrational levels of CO, have been identified and investigated. The branching ratios for the product channels C(P-3) + O(P-3), C(D-1) + O(P-3), and C(P-3) + O(D-1) of these predissociative states are found to depend on the electronic, vibrational, and rotational states of CO being excited. Rotation and e/f-symmetry dependences of the branching ratios into the spin-forbidden channels have been confirmed for several of the (1)Pi states, which can be explained using the heterogeneous interaction with the repulsive D'(1)Sigma(+) state. The percentage of the photodissociation into the spin-forbidden channels is found to increase with increasing the rotational quantum number for the K(4p sigma) E-1(+) (nu' = 0) state. This has been rationalized using a (1)Sigma(+) to (1)Pi to (3)Pi coupling scheme, where the final (3)Pi state is a repulsive valence state correlating to the spin-forbidden channel.