 This position led him to work in the underserved and far-flung villages and mountains in the war-torn area of Mindanao and Visayas.He served as a missionary doctor from 1989 until the late 1990s.Leo faithfully fulfilled his call despite the danger of being caught in the crossfire between the rebels and military and the difficulty of travelling three days by horseback riding, crossing rivers by bamboo barge and climbing mountains by foot.