Surat Thani —Police are hunting a man captured in security camera footage who they believe is the driver of the pickup truck that exploded on Friday night in the Central Festival Samui car park.
Investigators are also searching for eight former shopping mall security guards who were dismissed or recently quit their jobs while four others still working at the mall have been detained by soldiers for questioning.
These four are all from the southernmost provinces, according to officials.
"A review of security footage strongly indicates police have got the car bomb driver on camera," said Pol Maj Gen Somchai Nittayabowornkul, deputy commissioner of the Provincial Police Region 8 Bureau.
The police are trying to identify the suspect who was wearing a blue shirt in the footage before asking a court to approve a warrant for his arrest.
Pol Maj Gen Somchai is confident police will be able to track the man down in a day or two and so far there is no information suggesting he left Koh Samui after the bomb blast.
Based on the footage, the man in question left the shopping mall an hour after arriving at the car park. He was last seen on camera outside the shopping mall hailing a taxi to leave the area.
Pol Maj Gen Somchai said police are also looking for eight former security guards for questioning in connection with the explosion. Some of them were sacked while the others had quit.
According to the deputy commissioner, all 15 security guards on duty on Friday night have been questioned while three other security guards were being held by the military as of Sunday.
Meanwhile, a security source said that the 4th Army Region had detained one other guard for questioning.
The source said the four, who hail from the deep South, were taken to the Samui naval base for questioning to determine whether the Friday blast could be linked to the southern insurgency.
Pol Maj Gen Somchai said police are not ruling out any possible motives at this stage and the focus of the investigation will be more clear when they have the suspected driver in custody.
Authorities are working on three main theories including political violence and the southern insurgency after evidence suggested the Samui bombers could be linked to insurgent groups in the South and the fact the pickup truck used in the attack was stolen from Yala.
Pol Col Akaradej Pimonsri, acting commander of the Crime Suppression Division, which is leading the investigation, said the review of security camera footage from the shopping mall is 80% complete.
He refused to discuss further details but said the case would be resolved soon.
A source said the vehicle was seen entering the car park before opening hours, a time when only employees and vendors in the mall can enter the area.
The pickup truck was apparently parked in a blind spot for an hour before the man in the blue shirt emerged and was captured by a security camera.
According to the source, it is possible the driver was in the process of setting and arming the bomb during that hour.
Another source said a review of footage from surveillance cameras on the mainland suggest there might have been another pickup truck accompanying the stolen vehicle from Yala.
However, the second pickup truck was not captured on security cameras at the pier in Surat Thani's Don Sak district where the stolen vehicle boarded the ferry last Friday morning.
"We found another pickup travelling with the stolen car. It was possibly scouting the route for security checkpoints. But this second pickup was not seen to board the ferry to Samui island. It could have been waiting around to pick up the bomber," the source said.
Deputy government spokesman Maj Gen Sansern Kaewkamnerd said Monday the probe indicates the theft of the pickup truck in Yala had been staged.
The truck was reported stolen from Abdulrosa Dumeedae, a 52-year-old official with the La-ae tambon administrative organisation in Yala's Yaha district, about 8am on March 31.
"The theft of the pickup truck looks odd when compared to other thefts. Authorities suspect the owner is part of the plot," he said without elaborating.
Meanwhile, Pol Col Thewes Pluemsuth, superintendent of Bo Phut police on Koh Samui, has been moved to an inactive post at the Chumphon provincial police bureau.