On December 1, 2014, the "Sinai Governorate of the Islamic State" (formerly the Ansar Bait Al-Maqdis organization, which recently pledged loyalty to ISIS), took responsibility for killing American oil expert William Henderson. The message, posted on the organization's official Twitter account (@w_sinaa55), said: "We take responsibility for the killing of the American oil expert William Henderson in the Western Desert". The organization also published photos of documents carried by Henderson, including his American passport and a document issued by the Egyptian General Petroleum Corporation. The documents indicate that he worked for the Qarun Petroleum Company and was employed in Egypt by the Apache Corporation.
Photos of Henderson's identification documents distributed by ISIS
 See MEMRI JTTM "Sinai-Based Jihadi Group Ansar Bait Al-Maqdis Officially Joins Islamic State, Pledges Allegiance To Abu Bakr Al-Baghdadi," November 9, 2014.