Complete police investigation reports on the bombing and arson attacks in Bangkok and Nonthaburi will be forwarded to the prosecutor within 84 days, according to deputy national police chief Srivara Ransibrahmanakul.
His assurance came while national police chief Chakthip Chaijinda ordered tighter security measures in Hat Yai, the commercial hub of Songkhla as well as the lower South, during his visit to the city yesterday.
Pol Gen Srivara declined to say whether the police would transfer the investigations to the Crime Suppression Division as speculated, saying the decision lies with Pol Gen Chakthip.
There are currently nine arrest warrants out for a total of six suspects wanted in connection with the bombings and arson attacks, two of whom have already been arrested, said Pol Gen Srivara.
The court can allow detention of a suspect for up to 12 days for each investigation, but the detention time must not exceed 84 days in total.
If the investigation is still not finished at that point, the suspect must be released.
Investigators are waiting for more forensic evidence before deciding whether to press an additional charge of terrorism against the suspects, Pol Gen Srivara said.
The police are speeding up the forensic tests, including on samples taken from 17 cars, he said, adding that they are now handling about 80 such samples.
He neither confirmed nor denied media reports that another 18 people have been detained in southern border areas for interrogation in connection with the attacks.
Security has been tightened at tourist hubs such as the airport, public transport stations and shopping malls, said Pol Col Kissana Phathanacharoen, deputy spokesman for the national police office.
Additionally, police were inspecting shops selling materials similar to those used in the Bangkok attacks early this month, he said.
Police were also ordered to step up cooperation with local intelligence agencies, he said.