National Police chief, Chakthip Chaijinda, has ordered the Crime Suppression Division (CSD) to take over probes relating to the Aug 2 bombing and arson attacks in Bangkok and Nonthaburi and combine them into a single case, a source in the Royal Thai Police said.
Pol Gen Chakthip's decision to have the CSD take the lead in the investigation is based on findings which suggest the attacks were linked and may have been orchestrated by the same group of people, the source said.
The source also said that Pol Gen Chakthip has also instructed the CSD to work with the Office of the Attorney-General (OAG) on the investigation.
According to the source, the OAG is being drafted in because statements from detained suspects and gathered intelligence suggest the attacks were planned at a meeting held near the Thai-Malaysian border.
"The meeting was attended by the masterminds of the attack, as well as some fighters who managed to sneak across the Malaysian border into Thailand," the source said.
Under Section 29 of the Criminal Procedures Code, a representative from the OAG must be involved in probes relating to offences that happened on foreign soil.
CSD deputy chief, Pol Col Somkhuan Phuengsap, has been assigned as the lead investigator in the case. A known law specialist, his legal and investigative expertise will be needed to get to the bottom of the case, said the source.
On Aug 2, two suspects were arrested for allegedly planting two bombs in front of the police headquarters in Bangkok. The devices, which were set to go off at 8am on Aug 2, were successfully defused by bomb disposal officers.
In addition to the blasts which injured five people, arson attacks took place in Pratunam as well as in Siam Square. Police initially thought the attacks were linked to the insurgency in the deep South.