Father Eliseo “Jun” Mercado, a longtime Mindanao peace advocate, died Sunday due to a heart attack, according to his congregation, reported CBCP News.

The Philippine Province of the Oblates of Mary Immaculate (OMI) said the 72-year-old passed away at the Cotabato Regional Medical Center at 3:25 p.m.

Fr. Mercado had been hospitalized with complications from Covid-19 since May 8.

A day before his death, the congregation said the priest’s test result yielded negative for the virus.

He was also transferred to the hospital’s intensive care unit to complete his recovery.

“Things seemed to go well”, they said, when “suddenly his heart stopped due to heart attack”.

“Please pray for the repose of his soul,” said the OMI, describing Mercado as “one of our giants”.

“His presence and contribution to the Philippine Province and to the worldwide community of the Missionary Oblate of Mary Immaculate will be sorely missed,” it added.

Fr. Mercado was president of Notre Dame University in Cotabato City from 1992 to 2002. From 2003 to 2006, he served as Director for OMI’s Justice, Peace, and Integrity of Creation in Rome.

A known expert on the role of Islam in Southeast Asia and the Philippines, the priest had been extensively involved in the peace process in Mindanao.

Fr. Mercado was also actively involved with the Mindanao Task Force on Poverty Alleviation, the Social Reform Agenda Council for Central Mindanao, and the Presidential Commission for the Urban Poor for Central Mindanao from 1995 to 1998.

In 2006, the priest was a member of the 6-person delegation of the Union of Superiors General that visited South Sudan to formulate the Church response to the urgent pastoral needs following the signing of the Comprehensive Peace Agreement in 2005.

And in 2007, he also spent time as a consultant to the Sudan Catholic Bishops’ Regional Conference on peace-building, healing, and reconstruction.