Abu al-Hassan al-Qurayshi was reportedly captured in a recent raid in Istanbul. He had only been leader for three months after the death of Abu Ibrahim al-Quraishi, 45 (pictured).
The new leader of the Islamic State is the brother of its slain former caliph Abu Bakr al-Baghdadi, who served as his confidant, Islamic law adviser and messenger.
US military officials believe Abu Ibrahim al-Hashimi al-Qurayshi rigged the third floor of the building in preparation for an attack because the blast was much larger than one from a regular suicide vest.
Security officials and independent analysts believe there are four frontrunners to lead the terrorist group, including one extremist who was declared dead by the White House last year.