Round up their immediate families and their Immans and offer to trade them for the hostage. Start from there
FNC just said the 18 year old that turned himself in was being closely interrogated; and, that there are reports that Greg can’t confirm that he is the brother-in-law of one of the brothers.
I heard on FNC yesterday that the brothers lost both parents when they were young, lived in an orphanage for some time then went to a foster home. The father at the foster home converted them to Muslim (I seem to recall, but don’t quote me, that the foster father was somewhat radical, too). I’ve been thinking about him and was wondering where he was. If the gendarmes haven’t already done so, they should bring him in as well as the Inman at their mosque (as you mentioned).