John Mark Calilung is a Filipino government official. He is serving as a senior agent in the National Bureau of Investigation (NBI) of the Philippines, currently assigned to the agency’s Digital Forensic Laboratory Division and cybercrime investigation unit.

John Mark Calilung came to prominent public attention as a key witness for the House prosecution panel during the Senate impeachment trial of Vice President Sara Duterte. As part of his official duties, Calilung was tasked with leading the investigation and forensic authentication of a controversial online livestream broadcast by the Vice President, where she allegedly made grave threats and discussed an assassination plot against President Ferdinand Marcos Jr., First Lady Liza Araneta-Marcos, and former House Speaker Martin Romualdez. Testifying before the Senate impeachment court, Calilung and the NBI digital forensics team formally confirmed that the expletive-laden video clips were authentic and free from any digital alteration or artificial intelligence manipulation.

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