MANILA (UPDATE) - Mindanao Development Authority Secretary Datu Abul Khayr Dangcal Alonto passed away Thursday night at age 73.

Alonto underwent angioplasty operation, but his body succumb to complication due to pneumonia, according to former ARMM Assemblyman Zia Alonto Adiong.

Alonto's remains will be flown back to his hometown in Lanao Del Sur Friday.

Alonto's appointment as the first Muslim chairperson and secretary of the Mindanao Development Authority (MinDA) brought to the fore timely Bangsamoro representation in the overall socioeconomic development of Mindanao.

In Feb. 2014, the original members of the Moro National Liberation Front (MNLF) Central Committee installed Alonto as chairman of the MNLF.

He was a staunch supporter of the Bangsamoro Basic Law, a bill deliberated in the 16th Congress of the Philippines, which seeks for the establishment of a proposed new autonomous political entity, known as the Bangsamoro Autonomous Region, to replace the current ARMM.

Alonto was the second son born to the first Lanao del Sur governor, Ambassador Abdul Ghaffur Madki Alangadi Alonto, and Bai Hajja Rasmia Indol Dangcal, in Marawi City on Oct. 30, 1945.

He studied political science at the Cairo University in Egypt, but was a San Beda College Law student when the "Jabidah Massacre" occurred on March 18, 1968. Immediately after the incident, he organized the LAM ALIF, a Muslim youth group of which members became the core leaders of the Moro National Liberation Front (MNLF).

Alonto was elected as vice mayor of Marawi City in 1972, acting city mayor of Marawi in 1974, before being sworn in as the city's chief executive.

He was also elected as assemblyman in 1979 and sat as the interim head of the Regional Autonomous Government and subsequently elected speaker of the Regional Legislative Assembly, in absentia after he resigned as the interim head of the Regional Autonomous Government. - Report from Ron Gagalac, ABS-CBN News