The shop's assistant Pornchai sae Kuay, who has worked for the shop for more than 20 years, Sunday told police that Sang-arun was the most suspicious because the shop never had any conflict with anyone before.

"While she worked here, she often brought her Laotian boyfriend here," Pornchai said. On Saturday, Kim Jia Hua Gold Shop was closed because its owner went to Udon Thani for a merit-making ceremony.

At around 1 pm that day, witnesses saw two men moving a cooking-gas cylinder into the shop.

Police said neighbours did not get suspicious until late Saturday night when smoke and gas smell flew out of the shop. A neighbour then knocked on the gold shop's door, ringing the bell and shouting. After she did not get any answer, she alerted police.

Shortly after 11 pm, police and fire fighters arrived at the scene. The shop was locked from the outside.

After they broke open the door and cleared some of the smoke out, they found that three cooking gas cylinders were left running and one of them already consumed by the fire inside the shop. More than 40 gold necklaces were scattered on the floor along with broken glass pieces.

The shop also suffered minor damages from the fire.

The large safety box at the shop, which measured one metre in height, was cut open and the contents were stolen. Jinda Sirapattanakul, 50, her daughter Pawana, 22, and Sunita Maithong, 41, were found dead inside the shop.

They died of severe wounds to their skulls, crushed by hard objects.

Sunita was married to Pirom Maithong, the shop's goldsmith and supervisor. She was allowed to stay at the shop because she used to work here before. Jinda is a maid while Pawana is a sales assistant

Working for the shop for more than 10 years, Pirom was not at the shop when the crimes took place because he was running some errands in Chon Buri.

Pirom also suspected that someone who had inside knowledge about the shop was behind this brutal crime.

"There are more than 7.5 kilograms of gold as well as some cash in the safety box," he said.

Pol Lt Col Songsak Soopanich, an inspector at Chakrawad Police Station, said four false teeth were found in the shop.

"They apparently belonged to a man and they should belong to an attacker. No one in the shop has had false teeth," he said. He added that Jinda also grasped some hair of her attacker in her hand.

Songsak said police would submit the false teeth and the hair for DNA tests in a bid to bring the culprits to justice.

He added that police would check video recordings from the shop's closed-circuit television even if it was turned off on Saturday. "We will check what has happened in the days before the attack," Songsak said, adding that police also examined recordings from a security camera installed by police at a nearby location.

Metropolitan Police commissioner Pol Lt Gen Viroj Chanrangsi believed the attackers left open the cooking gas cylinders in the hopes of causing fire, which could have destroyed evidences and cover up their crimes.

"We are urgently investigating this case," he said.

Gold-shop owner Permsiri Wongprakrom, 67, said the victims had worked for her for many decades and they usually stayed at the shop. Permsiri herself lived in her house in Phra Khanong district.

The Nation