Warin Saengchan was preparing to run for the newly established Thai Nation Power Party in this year's poll.
According to police, at least two black-clad men raided Warin's house in Moo 7 in Kabang district at about 9pm on Sunday night (Jan 13). His wife, who was working in front of the house, was not aware of their arrival because they entered the building from its backyard.
Warin and his five-year-old son were watching television when the attackers broke into his home.
The intruders "talked about something" with Warin but their dialogue soon descended into a quarrel, which prompted his wife to enter the living room, officers said.
Her husband was tied up and shot. The gunman also killed his wife, Rokiyo Sapaeing, police said. Their son managed to flee with his 16-year-old sister.
A police inspection of their home found 11mm shell casings from a pistol.
Officers from Kabang police station and a special unit tasked with handling the southern insurgency are jointly looking into the murder, said Kabang police chief Pol Col Prayong Khotsakha.
Investigators believe Warin's death stemmed from a conflict he had become embroiled in while preparing for the poll.
Because the incident erupted in the insurgency-torn province of Yala, the investigators were searching for any possible links, the source said.
Warin was a native of Pattani's Panare district but he moved to Kabang after he married.
In a related story, the chief of Na Pradu police in Pattani's Khok Pho district has been transferred to an inactive post following a brazen attack on his police station in broad daylight. One of his subordinates was killed.
The station's sentry post was stormed by a group of unidentified men on Sunday afternoon who shot Pol Sgt Chaloemphon Khomkham, 33.
The incident was considered a case of "negligent" security measures, and Na Pradu police chief Amphai Chumchuai must take responsibility, police spokesman Pol Lt Piya Uthayo said, referring to an order given by the Provincial Police Region 9 chief.
The mastermind behind the attack is believed to be the leader of the Runda Kumpulan Kecil (RKK) guerrilla group. Police have so far made seven arrests.
Read full story here.