The Philippine president's claim spread quickly, with much of the local and foreign press reporting it as fact. Soon, unconfirmed reports of "beheadings" became a major part of the story line.
Asked to comment on the declaration of martial law on the southern island of Mindanao, Susan Thornton, acting assistant secretary of state for East Asian and Pacific affairs, told journalists Friday in Beijing that she "wouldn't want to second-guess what you would do in a situation where you have people being beheaded on television and church groups taken hostage."
But the Malabang police chief is alive — The Washington Post spoke to him on Friday. And The Post could find no new evidence of televised beheadings on Mindanao, though unconfirmed accounts of beheadings are circulating widely online. (There have been beheadings there in the past, and a priest and some followers were indeed taken hostage this week, according to a Filipino bishop.)
It is not yet clear whether the police chief story was a mix-up or a careful bit of messaging. What is certain, though, is that the inaccurate report shaped how the martial law news was covered — and potentially how it was received by the U.S. government.
In the wake of Duterte's speech, the police chief story served as a rhetorical link between unrest in the southern city of Marawi and the global threat of radical Islamist terrorism — spurring a social media frenzy.
"One of the most troubling aspects of the aftermath of the Marawi siege is the rapid proliferation of fake news and deliberate disinformation," said Richard Javad Heydarian, an assistant professor of political science at Manila's De La Salle University. "It is a classic case of a crisis being blown out of proportion by self-interested parties with ulterior agendas."
Battles between Philippine security forces and Muslim insurgent groups have raged for years, but the fighting made international news this week when Duterte, cutting short a trip to Russia, declared martial law across Mindanao, an area home to more than 20 million people.
The fact that the police chief story proved false does not mean there was no real fighting.
On Friday, the Associated Press described armored vehicles patrolling the streets of Marawi on the hunt for one of Asia's most wanted militants, Isnilon Hapilon, who is believed to be in the area.
Images from the scene showed armed soldiers clearing houses and civilians fleeing town. Witnesses described being trapped inside by gunfire. A bishop said a local priest and 10 parishioners were taken hostage.
At least 44 people have died in the fighting, including 31 militants and 11 soldiers, AP reported Thursday.
However, with the conflict still unfolding, it is hard to separate fact from rumor from fake news.
On both mainstream and social media, credible reports have been combined with unverified rumors to suggest, among other things, that Islamic State fighters have made it to the Philippines and are rampaging across the country, beheading Christians as they go — a narrative that is not supported by evidence.
Leaders of the two insurgent groups battling the army, Abu Sayyaf and the Maute group, have sworn allegiance to the Islamic State, and Philippine officials said Friday that fighters from Indonesia and Malaysia are involved.
But Solicitor General Jose Calida stressed that the Philippine government has no evidence of a direct link to the Islamic State, also known as ISIS.
"Again, on the matter of ISIS, the president emphasized that there's ISIS footprint, but that does not confirm the clear presence of ISIS itself yet," Calida said.
Hours later, in a separate news conference, Duterte reportedly said the Islamic State was, in fact, on the ground.
Romeo Enriquez, the still-living Malabang police chief, meanwhile said he was "shocked" to hear the president report him beheaded.
He is not sure where the story came from but suspects he was mistaken for the former police chief, who was killed — but not, to Enriquez's knowledge, by decapitation.
Enriquez, who is in Marawi as the fighting continues, said he had yet to hear a confirmed report of a beheading.
With fighting ongoing, he said, it is hard to get facts straight. "It's normal to have miscommunications and misinformation while the situation is not yet okay," he said. "Everything is under investigation."
Kimberly dela Cruz reported from Manila.