The death of al Qaeda leader Ayman al-Zawahiri in a US drone strike on the Afghan capital Kabul has sparked curiosity about who can now take command of the terrorist organization. Sayf al-Adl, born in Egypt, is the most likely candidate. He is the sole survivor of a group of five al Qaeda veterans, named in the past as Zawahiri's deputy. But there might be a problem. Al-Adl is believed to be currently living under restrictions in Iran — a country that al-Qaida considers a staunch enemy. Jihadi Veteran A founding member of Al Qaeda and a trusted lieutenant to...