A blue-shirt suspect sought in connection with the Sathon pier blast in August used the southern Thai-Malaysian border for his escape, national police chief Chakthip Chaijinda said Sunday.
The suspect, identified as Zubair Abdullah, was seen on CCTV footage on the evening of Aug 17 nudging a package believed to contain a bomb into the water at Sathon pier, which caused an explosion the following day.
The Erawan shrine bombing, also on Aug 17, killed 20 and wounded 130.
Police have caught two key suspects -- Adem Karadag, also known as Bilal Turk, who allegedly admitted to being the man in the yellow t-shirt who may have planted a bomb-laden rucksack at the shrine, and Yusufu Mieraili, who allegedly confessed to detonating it.
Fifteen suspects remain at large.
Pol Gen Chakthip said he had assigned Pol Lt Gen Suchart Teerasawat, acting assistant police chief, to contact Malaysian authorities to find Mr Abdullah.
The police chief said his own inquiries found Mr Abdullah went to the southern area bordering Malaysia to make his escape.
He had spoken to human smugglers detained in Malaysia and they said they know Mr Abdullah.
Pol Gen Chakthip said more warrants could be sought in connection with the bombings.
Asked whether he gives weight to Uighur-related issues or domestic politics as the key motive behind the blasts, the police chief said the causes are overlapping. "Any causes remain possible," said Pol Gen Chakthip.
He said he had asked assistant police chief Srivara Ransibrahmanakul to take responsibility for the bombings probe.
Police have asked Interpol to help track down the suspects believed to have fled overseas, he said.
Four or five police teams are also on the lookout for Odd Phayungwong, a Thai suspect who police said supplied bomb-making materials for the explosions.
Mr Odd, according to police, had also been linked to two politically-motivated bomb attacks in 2010 and last year.
Teasing out supposed links between Mr Odd and domestic politics, a police source earlier said Boonchaliew Dusadee, a lawyer for several Pheu Thai Party executives, once sought bail for Mr Odd who appealed against a one-year jail sentence handed down by the Criminal Court on May 21, 2010, for violating the emergency decree during the 2010 red-shirt protests.
Mr Odd was granted bail five days later with a 40,000-baht surety placed by Mr Boonchaliew, the source said.
Winyat Chatmontree, a key lawyer with the United Front for Democracy against Dictatorship (UDD) during the 2010 demonstrations, said it was common for red-shirt lawyers at that time to provide assistance to protesters facing charges and Mr Odd was one of those who received help.
The financial assistance for the detained protesters came from many donors, he said.
Mr Winyat insisted Mr Boonchaliew was only a staff member of the legal team who helped seek bail for detained red-shirt demonstrators, but was not actually a lawyer.
"I have been unable to reach Mr Boonchaliew so far," Mr Winyat said. "I am trying to contact him." Police will likely to want to take a look at the bail document, if one can be found.
Meanwhile, a police inspector-general is investigating corrupt behaviour by the immigration police.
Pol Gen Chakthip, who recently took up the job of national police chief, pledged the probe would carry on.
Former police chief Somyot Poompunmuang ordered the probe following reports that Mr Karadag paid a $600 bribe (21,850 baht) to illegally enter Thailand.
Pol Gen Somyot also released a memo outlining six common corrupt behaviours of immigration police.
If the inspector-general conducting the probe discovers that any officers are involved in such offences, they will be punished, Pol Gen Chakthip said.
He would give weight to measures to prevent bad people from entering Thailand and deal with those who overstay their permits.
He admitted there are still flaws in the immigration police's operation. He said immigration officers are asked to ensure visitors can cross the border easily, but they must also attach importance to security issues.
Another issue is that Thailand has many natural border channels for entry and exit, he said.
Pol Gen Chakthip said he had assigned Pol Lt Gen Srivara to take care of the human trafficking issue instead of deputy police chief Ake Angsananont, who has taken up a new job as permanent-secretary to the PM's Office.
He said he also ordered Pol Gen Chaiya Siri-ampankul, acting inspector-general and deputy police chief, to deal with crooked police.