In one of the most devastating attacks in CIA history, officers failed to search an Al Qaeda double agent before he entered a December meeting at their base in a remote part of Afghanistan, and he detonated a huge bomb. Two contractors and five CIA employees were killed.A CIA investigation into a December suicide bombing in Afghanistan that killed seven agency personnel and injured six others found "systemic breakdowns" in the field and at headquarters, but no one will be fired or disciplined, CIA Director Leon Panetta said Tuesday.