Former Philippine President Rodrigo Duterte was arrested by police at Manila’s international airport Tuesday on order of the International Criminal Court in connection with a case of crime against humanity filed against him, the Philippine government said.

Duterte was arrested after arriving from Hong Kong and police took him into custody on orders of the ICC, which has been investigating the massive killings that happened under the former president’s deadly crackdown against illegal drugs. He returned after delivering a fiery speech to Filipino diaspora in Hong Kong, at a campaign rally on Sunday.