I wondered how many Christians attended a church where their murders were not even mentioned? If you did, I encourage you to pray about that. Christians in this country need to b outraged, loud, mad, etc...me included!! I am probably out of line....I am just so mad about it!!!
Perhaps some combination of praise of the Lord and begging Him to intervene in this situation.
He might grant the prayer, to show His love and power. There is bible precedent for this. But try to get as right as possible with the Lord before doing it, to remove obstructions to the prayer.
Our parish chanted special prayers for the dead Copt martyrs after the Liturgy last Sunday. Orthodox Christians across the world did the same. At the close of the Liturgy our priest gave a real stem winder of a sermon about the dangers to this country and all Christians of resurgent Mohammedanism. When he was done, the entire congregation applauded. Remember, however, that we are people whose families suffered (and suffer to this day) for centuries under the heel of Mohammedanism.