Abu Osama Al Masri (also referred to as Sheikh Osama al Masri), has been identified by intelligence sources as the likely mastermind behind the attack on a Russian airliner that crashed in the Sinai Peninsula in late October, killing all 224 passengers on board.

al-Masri is an Egyptian cleric who graduated from Egypt’s infamous Al Azhar University, a known hotbed for jihadi theology. It is the same place from where U.S. President Barack Obama gave his famous Cairo speech in 2009, shortly after being elected president.

In recent months, al-Masri – whose jihadi outfit used to be known as Ansar Bayt al-Maqdis (ABM), before switching allegiance to ISIS – has often called for fellow terror sympathizers to attack members of Egyptian President Abdel Fattah el-Sisi’s government.

On Sunday, British officials told the Sunday Times that the 42-year-old ISIS cleric is a “person of interest” in the suspected attack, adding that British forces may be utilized in a “kill or capture” mission targeting al-Masri.

In a statement following the suspected attack, al-Masri said the alleged bombing was a “blessing of our gathering under a single banner and leader,” in reference to the fact that the suspected attack also occurred on the one-year anniversary of the group pledging to follow ISIS chief Abu Bakr al-Baghdadi.

“We are the ones who downed it by the grace of Allah, and we are not compelled to announce the method that brought it down,” al-Masri said defiantly, following the Sharm el-Sheikh to St. Petersburg jet crashing in the desert.

al-Masri’s jihadi group, which in the past had strong ties to Al Qaeda and the Muslim Brotherhood, has rebranded itself as an ISIS affiliate. Throughout this process, the Sinai Province (of the Islamic State) has continued its insurgent effort primarily focused on Egypt’s military and police.

Before joining the caliphatist ISIS, ABM had more immediate regional goals, such as plotting attacks against Egypt and Israel, strengthening its alliances with the Palestinian terrorist group Hamas, and smuggling weapons into the Gaza Strip. Sinai Province has completed its objectives with some success, killing dozens over the past year alone and injuring hundreds more.

“Poison their food… Surveil them at home and in the street… destroy their homes with explosives if you can,” al-Masri said in a past message discussing Egyptian judges, a calling that was similar to countless more messages demanding the massacre of innocents.

ABM has been listed as a terrorist group by the United States and many other western nations. In November, 2014, the U.S. State Department added the Sinai Province as another alias of al-Masri’s terror organization.

In its initial terror designation of the Sinai-based organization, the U.S. State Department described the Islamic militant group as one that “shares some aspects” of Al Qaeda ideology and “generally maintains a local focus.”