Thai police hunt Bangkok bombing suspect spotted on CCTV video

Thai police are looking for a suspect captured on CCTV footage at the scene of Monday’s bomb blast in Bangkok, which killed at least 20 at a downtown Hindu shrine, including several East Asian tourists. 

The footage shows a man in a yellow shirt removing his backpack in the shrine and immediately leaving. "There is a suspect ... we are looking for this guy," Prime Minister Prayuth Chan-ocha said, according to BBC News. 

Theories about the bomber's identify are swirling. The intersection next to the shrine “has been the site of mass political protests” in the past few years and has been targeted by violence, but nothing of this scale, according to CBS News. "It is much clearer who the bombers are, but I can't reveal more right now," said Defense Minister Prawit Wongsuwan Tuesday. "We haven't ruled out terrorism."

Matthew Wheeler, Southeast Asia security analyst for the International Crisis Group, told CBS that the attack “doesn't bear the trademarks of typical violence over the past decade from political instability or Muslim separatists.”

"It is certainly not like politically motivated attacks we've seen in the past which have generally been designed to grab attention but not cause casualties," he said.

CBS explains:

Thailand has seen many violent attacks in recent years, particularly through a more-than-decade-long insurgency by Muslim separatists that has left more than 5,000 dead in the country's deep south. Those attacks have never extended to the capital, however.

Bangkok has seen politically charged violence over the past decade; the deadliest, in 2010, killed more than 90 over two months and was centered on the same intersection where Monday's bomb went off. But none of those attacks included a bomb blast that seemed intended to produce mass casualties.

The BBC cited other experts explaining why various perpetrators were unlikely.

Analyst Pavin Chachavalpongpun, an associate professor at Kyoto University's Center for Southeast Asian Studies, said he believed that it was unlikely a domestic group was behind the blast because Thailand’s Buddhist culture values religious tolerance too much for any Thai to attack a holy site; the scale is much larger than any point a domestic group would need to make; and the Muslim separatist conflict of the south is very localized. 

The scale of the damage is too much, too great, too messy. If someone wanted to fulfill a domestic agenda, such carnage would be unnecessary.

Thailand has seen incidents in the past where someone might throw a grenade that injures a few people to get their political message across, but that is where it has generally ended.

Mr. Chachavalpongpun also dismissed the possibility that it was carried out by members of China's Muslim Uighur minority, some of whom have sought refuge in Thailand. A group of Uighurs was recently deported to China. 

The Guardian writes that security officials have also dismissed the possibility it was Malay separatists in the south because the bomb allegedly used – a 3kg pipe bomb – is not in their arsenal.  

A crackdown on dissent since a May 2014 coup, including the arrest of hundreds, had brought calm to Bangkok after months of violent protests. However, tensions have risen over the timing of an election that the ruling junta had pledged to hold by this year. That timetable may slip back as late as 2017, the Guardian reports.