Councilor Abdul Katab, alias Henry, has been charged with multiple murder and multiple frustrated murder, along with Suharto Ahmad, owner of an explosive-laden motorcycle used in the bombing.
Parang Mayor Vivencio Bataga said he is certain that the attack was aimed at "neutralizing him."
Bataga, who suffered 27 shrapnel wounds in different parts of his body, is recovering at the Notre Dame Hospital in Cotabato City.
Bataga, a former Army colonel who had fought secessionists in Mindanao, has survived three previous assassination attempts.
Philippine National Police chief Director General Hermogenes Ebdane Jr. said the Katab and Ahmad had been hired by a political rival of Bataga, one of about 81 wounded in the attack.
Police said Ahmad is the owner of the motorcycle where the bomb was hidden, while eyewitnesses had identified Katab as the man who drove the vehicle and parked it near the gymnasium.
Ebdane said the entire province of Maguindanao had been declared an "area of concern" with police special units to be deployed to ensure that elections would be peaceful.
During a meeting yesterday at the provincial capitol in Shariff Aguak, Maguindanao Gov. Andal Ampatuan told Ebdane that local leaders are helping police look for the suspects.
Ampatuan had offered "earnest money" in exchange for any information that would lead to the arrest of the bombers and their accomplices.
Police are hot on the trail of the suspects, who were last seen leaving their homes hours after an explosion ripped through the gym packed with people watching a basketball game, he added.
Senior Superintendent Isnaji Bantala, Autonomous Region in Muslim Mindanao police director, said Katab, who hails from nearby Bonggo island —a predominantly Muslim area — has disappeared after the bombing and his relatives could not give any information on his whereabouts.
Ebdane and a dozen key PNP officials were here the other day when charges were filed against the suspected bombers.
Among those killed in the bombing were a pregnant woman, who belonged to the influential Tomawis clan here, a son of a vice mayor in nearby Barira, Maguindanao, and a soldier assigned as security escort of Bataga.
Military intelligence sources said Katab is also the suspected mastermind in two bombings here last year, which also targeted Bataga. — With Christina Mendez, AFP