Why has Obama done nothing about the murder of Border Agent Brian Terry?

The Obama administration was involved in a gun running operation which put thousands of automatic weapons as well as .50 cal sniper rifles in the hands of Mexican drug lords. Two of those weapons which were allowed to cross the border were found at the Brian Terry murder scene. Why has Obama done nothing to those responsible, namely Holder and Napolitano? Obama said he knew nothing about the operation (yeah, right) so why is he doing nothing?