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Alan Peter Cayetano, a senator judge but who sounded like he was lawyering for the defense, tried in vain to make the expert witness admit that the threat was conditional.
The witness was placid: he said the threat was absolute.
Cayetano having failed that, defense lawyer Carlo Narvasa tried to break the expert witness’s testimony on the third day of the Sara Duterte impeachment trial. Narvasa wanted to zero in on an aim: to prove that the witness’s transcription of the Sara assassination threat against the president and first lady was simply, poor work.
The witness answered plainly: let’s listen to the recording. And there were the “sloppy” parts – garbled words that couldn’t be transcribed. Narvasa failed.
The Sara defense team was on a rampage to destroy John Mark S. Calilung, Investigation Agent III of the National Bureau of Investigation. It was he who was tasked by the NBI to perform a digital forensic of the recording in November 2024 when Sara uttered the threat during a Zoom meet with media.
Calilung joined the NBI in August 2021. He was previously an Audit Supervisor in a private firm. He is an accountant, an alumnus of Central Luzon State University in Nueva Ecija (he has two college degrees). He is a native of San Leonardo, Nueva Ecija. In the May 2017 CPA Licensure Examination, his grade was 86.67%.
But why must Calilung’s testimony be destroyed? It is not only because it is an expert testimony. If it stands the test of truth, it has the potential of opening the floodgates to a Sara Duterte conviction.

Hence, like Cayetano before him who sounded like a defense lawyer, Robin Padilla asked the Presiding Officer for Calilung’s credentials. Meaning, was he a real and verified expert witness?
As if on cue by Padilla, Calilung’s credentials “fell on my lap.” My source is confidential. Shall we just safely say that it came from a legitimate government agency?
On his official curriculum vitae submitted to government, Calilung listed the professional trainings he had received that now give him the merit of an expert witness.
Digital Security Challenge: Interpol
Capacity Development Program on Case Build-up for Law Enforcers: Department of Justice
Online Table Top (TTX) on Cybercrime: Interpol
Online Investigation Workshop: United States Department of Justice
UNDoc Digital Evidence for Front Line Investigators: United Nations Office of Drugs and Crime
Padilla shouldn’t have asked for Calilung’s CV. Now Padilla has a monkey’s wrench: defending Sara Duterte.
The views in this column are those of the author and do not necessarily reflect the views of VERA Files.