Now is the time for all moderate, i.e., non-murderous, Muslims to speak out and go on record as being opposed to jihadist murder. Why wouldn't they? Indifference, fear, or complicity. But since silence means assent, we'll have to go with complicity.
By the way, in case you find yourself in Sochi, note that in the attached CBS report naming Ruzana Ibragimova as a suspect, the woman in the photo without the headscarf does not look exactly like the woman in the photo with the headscarf, and it's not just the scarf. Observe the fullness of the lips, angle of the eyes, shape of the nose.