Many details descoverd of The Yemeni Islamic extremist, Khalid Abdul Nabi, who described as the "black box" of al-Qaeda in Yemen after he surrendered himself to the security forces in the Yafi region of southern Yemen  after he led a terrorist organization  claimed the so-called "Aden Abyan Islamic Army" and his allegiance to Osama bin Laden, And Abu Bakr al-Baghdadi the leader of ISIS.

According to Yemeni reports, "Abd al-Nabi" was born in the Yazidi tribe in the Yafi region of the province of Lahj in northern Aden, part of the region of Labus, and in 1998, founded the so-called Islamic Army Abyan in south of Yemen.

The sources added that despite his allegiance to Osama bin Laden, and his relationship with a number of prominent leaders of the al Qaeda in Yemen and abroad, "Abdul Nabi" preferred to be free without joining a specific organization, providing only logistical and material support to any of the fundamentalist groups.

He joined with other Yemenis the Islamic militants belonged to Islah party in the so-called "unity" war against the separatists in the summer of 1994, along with government forces, in conjunction with the bilateral agreement that brought together Ali Abdullah Saleh and Abdul Majeed al-Zindani who used to be wanted by US in 2000 to call on radical Yemeni militants from Afghanistan to take part in the fighting in Yemen.

 
His name was associated with many of the violence in Yemen, including bombings and assassinations of security officers, along with the kidnapping of 16 foreign tourists, in 1998, which resulted in the deaths of four hostages, and the elements associated with the suicide bombing on the USS Cole, on 12 October 2000 , While anchoring the Yemeni port of Aden.

The attack killed 17 US sailors. His group emerged in June 2003 in the confrontations of the rugged mountainous hilly, where Abd al-Nabi adopted the Hattat Mountains in Abyan province south of Yemen as a fortress for him and for his armed group and fighters.

In August 2008, Yemeni security forces clashed with members of Abd al- Nabi in Abyan province, killing five of his men and arresting 28 al-Qaeda supporters, including Abdel Nabi.
Khaled agreed to enter into a dialogue with the Yemeni former president Ali Abdullah Saleh, resulting in a bilateral agreement that would support him in his fight against the rebels in the north and the separatists in the south in exchange for his release and all his combat elements. To be released in 2009 as part of a general amnesty of about 175 Islamic militants, and returned to Abyan, the center of his strength, to restore his influence again and gather the ranks of fighters.

On his relations with Usama bin Laden, Abdul-Nabi, nicknamed "Abu Bakir", met with al-Qaeda leader Osama bin Laden to announce loyality to  al Qaeda leader  before joining the fighters in Afghanistan in 1990 and accompanying Osama bin Laden in Peshawar.

He returned to Yemen in 1994 with a group of fighters loyal to Osama bin Laden and on his orders to participate in the separatist war. Although he is linked to Usama bin Laden, he refused to join the Yemen-based Ansar al-Sharia organization, which has different ideological and administrative reservations.

However, this did not prevent the continuation of his close relationship with the mother organization and all its prominent leaders in Yemen, and then intensified differences Khalid Abdulnabi with the organization "supporters of the law" until it reached the hostility and estrangement after his support and pledge to "Abu Bakr" Baghdadi, leader of ISIS, "Daash" Under the new Caliphate.

Abdu Alnabi announced loyalty to  "Abu Bakr" Baghdadi the leader of ISIS .