Chief Inspector Bernard Baui, this towns police chief, said former Diffun policeman Fernando Dionisio is now under the custody of the Criminal Investigation and Detection Group (CIDG) based in Santiago City, Isabela.
A witness has tagged Dionisio as the alleged triggerman. He has refused to undergo a paraffin test.
Geronimo Bautista, president of the provinces Liga ng mga Barangay, was gunned down with an M-16 Armalite as he was about to enter his residence.
Dionisios family, however, denied the accusations. His eldest daughter Bernadeth said her father was at home when the crime happened.
She pleaded to investigators to look deeper into the incident to unmask Bautistas real killers.
"May iba pa namang kalaban sa pulitika si chairman Bautista, hindi lang si papa (Chairman Bautista also had other political rivals, not only my father)," she said.
Meanwhile, unsigned leaflets bearing the logo of the communist rebels Quirino Front have been scattered at the towns public market, stating that the guerrillas were responsible for Bautistas killing because of his alleged abuses against ordinary people.
Municipal officials, however, doubted the authenticity of the supposed statement of the insurgents.
"Gawa-gawa lang yan ng mga taong gustong manggulo ng imbestigasyon (Thats only the handiwork of people who want to muddle the investigation)," said a municipal councilor, who refused to be identified.