  Kinetic energy and angular distributions of O$^-$ ions formed by dissociative
electron attachment to CO molecule have been studied for 9, 9.5, 10, 10.5, 11,
11.5 eV incident electron energies around the resonance using time sliced
velocity map imaging spectrometer. Detailed observations clearly show two
separate DEA reactions lead to the formation of O$^{-}$ ions in the ground
$^{2}P$ state along with the neutral C atoms in ground $^{3}P$ state and first
excited $^{1}D$ state, respectively. Within the axial recoil approximation and
involving four partial waves, our angular distribution results clearly indicate
that the two reactions leading to O$^{-}$ formation proceed through the
distinct resonant state(s). For the first process, more than one intermediate
states are involved. Whereas, for the second process, only one state is
involved. The observed forward-backward asymmetry is explained due to the
interference between the different partial waves that are involved in the
processes.
