Eleven of the 19 cadavers recovered following the encounter in Toboso, Negros Occidental, tested positive for gunpowder residue, according to the Philippine National Police’s regional forensic unit.

PNP-Negros Island Regional Forensic Unit chief PCol. Reynaldo Calaoa, in a press conference on Thursday, said the findings were based on paraffin tests conducted on the retrieved bodies.

“Hindi porket nag-test negative sa gunpowder ay hindi nagpaputok,” Calaoa said, stressing that a negative result does not automatically mean a person did not fire a gun.

He explained that several factors could lead to a “false negative” result in gunpowder residue examinations.

“Meron kasi na tinatawag na false negative, ibig sabihin po may mga factors kung bakit nag-negative ’yan,” he said.

Calaoa noted that many of the cadavers had been immersed in water, which may have affected the results of the forensic examination.

“Most of them are immersed sa tubig, ibig sabihin, nabasa yung kamay niya,” he added.

He also cited firing distance as another factor, saying that suspects who fired from afar may not leave detectable traces of gunpowder residue on their hands.

“Another one to consider is yung distance, yung layo, kasi malayo,” Calaoa said.

He declined to release further details regarding the identities of the fatalities who tested positive for gunpowder traces.