Banisilan Mayor Floro Allado was detained at the North Cotabato police headquarters in Amas District, Kidapawan City.
Piñol said charges of multiple murder and frustrated murder will be filed against Allado by the provincial prosecutor tomorrow.
"I will personally monitor the filing of the criminal case against Mayor Allado," he said.
Gen. Nehemias Pajarito, commander of the Army’s 6th Infantry Division, has deployed a peacekeeping contingent from the 7th Infantry Battalion to prevent hostilities from escalating in Banisilan, located at the boundary of North Cotabato and Lanao del Sur.
Accompanied by officials of the North Cotabato police, Piñol fetched Allado from Banisilan last Friday and escorted him to the provincial Capitol in Kidapawan City where he first underwent an inquest by state prosecutor Agerico de Guzman.
"The provincial government will see to it that justice will prevail. I will flex my authority, as provided for in the Local Government Code, to punish whoever has done wrong in that incident," Piñol told reporters.
He said Allado would have to be detained at the Midsayap municipal jail after the filing of charges against him because his town is under the jurisdiction of the Midsayap municipal trial court.
Lt. Col. Julieto Ando, spokesman of the 6th ID, said Col. Jeavy Resurreccion, who has extensive experience in diplomatic initiatives with feuding Moro families, led the peacekeeping force that Pajarito has deployed in Banisilan.
According to Banisilan councilors, three Muslim villagers — Tiburon Kadil and two others identified only as Kush and Katindig — were killed while six others were wounded when Allado and civilian volunteers opened fire on a truck they thought were carrying armed men identified with a rival politician.
One of the wounded passengers later died while undergoing treatment at a hospital in Wao, Lanao del Sur.
Allado denied the allegation, saying the civilian volunteers merely foiled an attempt by heavily armed men to take over the town proper.
Allado said the gunmen arrived in Barangay Poblacion II, the center of Banisilan, and opened fire at him when he and the civilian volunteers tried to accost them for illegal firearms.
"They were armed with M-16 and M-14 assault rifles," Allado said in a radio interview.
Jennifer Makalingkag, chairwoman of Barangay Poblacion I where the incident took place, said the two armed men on board the truck were duly registered civilian volunteers from a nearby barangay.
Witnesses took turns telling Catholic radio station dxND in Kidapawan City that after the shooting, Allado sprayed bullets on his vehicle to make it appear that the truck passengers opened fire at him first and provoked the firefight.
Makalingkag said the victims were rice traders, who were merely having their truck filled up at a gas station when Allado’s group arrived and opened fire at them when they noticed that two of the men were armed.
Muslim religious leaders in Banisilan have confirmed that Allado earlier had a fistfight with the president of the town’s Association of Barangay Chairmen.