Four employees of a pest-control company have become prime suspects in the blaze that erupted on the 10th floor of the Siam Commercial Bank (SCB) headquarters in Bangkok on Saturday night. They were reportedly the last people on that floor before the fire started.
A police source said they had been summoned yesterday and admitted being in the area where the fire broke out. The source quoted them as saying that the sprayed chemical may have hit machines and sparked the fire.
"Police will check the scene and footage from the security cameras installed there. If all findings point to these four, then they and the owners of the pest-control company will be charged," the source said.
Meanwhile, Forensic Science Office chief Pol Maj-General Thawatchai Mekprasertsuk said investigators have found no signs of irregularity, flammable substances or even petrol on the 10th floor of the SCB building, though arson has not been ruled out yet.
The fire damaged a 10-by-15-metre area of a 10-by-30m room. The area damaged was where documents of approved loan contracts were placed.
Police are studying footage from the security camera to see if people from a pest-control company entered the room and if their work caused incendiary sparks or affected the building's fire-prevention system, he added.
Investigators should determine the cause of the fire by next week, Thawatchai added.
Another source from Phaholyothin Police Station, whose jurisdiction covers the SCB complex, said spraying equipment has been seized and investigators are looking to see if the mosquito spray used was flammable. Staff members of this unnamed company and its owners will be charged with carelessly causing fire if investigation results point that way, the source said.
Speculation over link to KMITL scandal
This fire has been linked to a key issue the bank is involved in - a police probe into a high-profile theft of more than Bt1.6 billion (S$66.5 million) belonging to King Mongkut's Institute of Technology Latkrabang (KMITL), most of which was deposited in three SCB accounts.
SCB has been attacked by KMITL students and staff, who accuse the bank of not cooperating by providing them with documents they have requested.
Meanwhile, there has been public speculation on social media that the fire may have been arson - to get rid of crucial bank or transaction documents that might solve this much-debated scandal.
A senior investigator, Pol Maj-General Korkiat Wongsumeth, said that 45 people including SCB employees and the mosquito-spraying staff had been interviewed. But police needed to rely on expert opinions on the likely cause of the fire and solid evidence, before making a conclusion on whether criminal action is taken.
He said the reports and professional recommendations on post-fire structural strength would be supplied by Bangkok's Department of Public Works and Town & Country Planning, while the final conclusion on the cause of the fire would be made by the police's Office of Forensic Science.
The Engineering Institute of Thailand under HM's Royal Patronage said the mosquito-spraying work was probably the reason for the fire.
But senior EIT official Bussakorn Saensuk said its staff would enter the scene of fire today and take two weeks to reach a conclusion on the actual cause of the fire.
SCB issued a statement yesterday citing remarks by Thawatchai, which discounted a theory about an arson attack.
The general was quoted as saying that the fire started and burned slowly at the scene whereas in arson attacks fires burn quickly and spread into other areas.
SCB would work out a repair plan to renovate the floor and sent it to the Bangkok Metropolitan Administration for approval, the statement said.