  We examine the significance of $2 \rightarrow 2$ partonic collisions as the
suppression mechanism of high-energy partons in the strongly interacting medium
formed in ultrarelativistic heavy ion collisions. For this purpose, we have
developed a Monte Carlo simulation describing the interactions of
perturbatively produced, non-eikonally propagating high-energy partons with the
quarks and gluons from the expanding QCD medium. The partonic collision rates
are computed in leading-order perturbative QCD (pQCD), while three different
hydrodynamical scenarios are used to model the medium. We compare our results
with the suppression observed in $\sqrt{s_{NN}}=200$ GeV Au+Au collisions at
the BNL-RHIC. We find the incoherent nature of elastic energy loss incompatible
with the measured data and the effect of the initial state fluctuations small.
