The high-profile spouses of ISIS killers often have surprising backgrounds from bikini-wearing sun worshipers to band that is guitar-toting.

ISTANBUL—On the CCTV footage released by Turkish police, the widow of just one associated with the Islamic fanatics in charge of last week’s terror rampage in Paris comes across as prim, even drab, as she goes through passport control in the airport here. Hayat Boumeddiene’s tightly drawn white headscarf and hooded coat is a cultural[…]