Relatives of the victim, Eric Lubao, 40, a follower of Liberal Party mayoral bet Jay Perez, suspect that the killing was politically motivated.
Lubaos younger brother Isagani told investigators that the victim had received text messages from unknown people supposedly telling him to stop supporting Perez, or else something bad might befall him.
Police said the gunman broke a window of Lubaos house in Barangay Sto. Cristo and from there aimed his firearm at Lubao, hitting him four times.
Probers were exploring all angles but revealed that Lubao had a long-standing feud with a group which they did not identify.
Mayor Ruben Guce, of the Lakas-CMD (Christian-Muslim Democrats), denied any knowledge of Lubaos gunslaying.
"I dont have the capacity to do such a thing. Wala akong (I dont have) goons, gold and guns," he said.
"Gawa-gawa na lang yan ng mga naghahabol sa kampanya. Alam nilang nauungusan ko na sila ng malayo (Thats the handiwork of people running after me in the campaign. They know that I have far overtaken them)," he said.
Guce added: "Wala namang maniniwala dito sa San Jose na maaari kong ipagawa yon at labag yon sa aking religious upbringing (Nobody here in San Jose would believe I could have ordered that. Besides, doing such a thing is against my religious upbringing)."
"I-research muna nila kung ano ang trabaho ni Eric bago nila ako akusahan ng kung anu-ano (They should research what Erics work was before they accuse me of anything)," Guce said.
Police found seven empty 9-mm. shells and two deformed 9-mm. slugs at the crime scene.