Senior Superintendent Nelson Nario, Isabela police director, said the ambush victim, Romy Blancaflor, Jones municipal chairman of the Aksyon Makamasa party, sustained four gunshot wounds two in the head and two in the chest.
Blancaflors cousin was also shot dead a few days after the special congressional poll here last May.
Police said the ambushers left Blancaflors wife and two children unharmed.
Nario said he has sent a composite team to Jones town, some 30 kilometers from this city, to help in the investigation and gathering of evidence.
He said Blancaflors killing might have something to do with politics, adding though that investigators are looking into other angles.
Blancaflor was a partymate of Santiago City councilor Anthony Miranda, founder of the Aksyon Makamasa party.
Miranda, who is eyeing the provinces fourth congressional district in next years elections, is the youngest brother of Santiago City Mayor Jose Miranda, founder of another local political party, Kalikasan (Kalipunan Para sa Kaunlaran ng Santiago), which is affiliated with the Partido ng Masang Pilipino of former President Joseph Estrada.
Before he was killed, Blancaflor had reportedly been actively floating the young Mirandas name in Jones since the latter signified his intention to run for congressman in next years polls.
The fourth congressional district, which includes the municipality of Jones, is currently represented by Rep. Giorgidi Aggabao, who won in special elections last May over Dr. Asuncion Abaya, widow of the late Rep. Antonio Abaya whose death last February resulted in the holding of the special poll.
Mrs. Abayas candidacy was supported by the Mirandas, while Aggabao ran under the Nationalist Peoples Coalition, whose president is Isabela Gov. Faustino Dy Jr.
Abayas camp contested the results of the special elections, alleging fraud. They have a pending electoral protest with the House of Representatives Electoral Tribunal.
A few days after the special elections, Blancaflors cousin, engineer Joaquin Soriano, coordinator of Bayan Muna party-list group in Jones town and a campaign manager of Mrs. Abaya here, was shot dead by seven unidentified men in front of his house in Jones.
"We knew Blancaflor very well, not only as a member of the Aksyon Makamasa in the fourth district but also as an active community leader. His charisma with the masses was really very strong. We believe his killing was politically motivated," said a close aide of councilor Anthony Miranda.