  We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0
K^- processes. We investigate the possibility that supersymmetric CP violating
phases can affect our determination for the angle \gamma in the unitary
triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and
chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a
model independent way by using the mass insertion approximation method. We also
revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between
the first and second generations of the up sector. We emphasize that in case of
negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous
contributions from more than one mass insertion in order to be able to obtain
the CP asymmetries of these processes within their 1\sigma experimental range.
However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation
between the two asymmetries and it becomes natural to have them of order the
central values of their experimental measurements.
