"Lay down your weapons and holy symbols. Until we determine who the traitors are, you are all suspects."
Note that Ari's detect evil is continuously active in a 1400 yd radius and ignores efforts to conceal alignment (level 7 spells or less is automatic, higher than that requires an opposed caster level check). I single out those carrying the items that trigger the detect evil and pull them aside Literally, if I have to..