Suspects' DNA in Deadly Thailand Bombing Turns Out Not to Match Evidence

Forensic tests on two suspects have failed to find a link to the site of Thailand's deadliest bomb attack, police said on Friday, dealing a blow to the investigation.

DNA examination of the two foreigners tie them to a stash of explosives found in a Bangkok apartment block, but not to evidence collected at the Hindu Erawan Shrine where 20 people were killed August 17, police said in a televised announcement. The lack of a link complicates a high-profile case shrouded in mystery, with authorities no closer to establishing a motive for the attack carried out in one of Bangkok's busiest commercial areas.

The military has speculated the perpetrators could have been members of a human trafficking gang frustrated by a police crackdown. Thailand has rejected the possibility that a militant group was involved.

Related: Body Parts and Pools of Blood Visible at Tourist Site Targeted in Bangkok Bombing

Thai authorities arrested a suspect on August 29, but claimed he was not cooperating with interrogators. The arrest came after police raided the man's apartment, where they reportedly found bomb-making materials and more than 200 forged passports.

The man's identity has not been revealed, but he has been described as a "foreigner," and police are reportedly considering the possibility that he was part of a network that provided fake passports to migrants. All of the fake passports were reportedly from the same country, though police did not say which.

Police were testing DNA samples of the second of two foreigners to establish if he was the chief suspect — a yellow-shirted man caught on surveillance footage placing a rucksack at the shrine before the explosion.

"There's no evidence to confirm he is the yellow-shirt man," police spokesman Prawut Thawornsiri told reporters. Prawut did say, however, that police believed he was "definitely involved in the bombing."

Police seized a large amount of bomb-making material in raids on two buildings in north Bangkok, but nothing that ties the two men, whose nationalities are unknown, directly to the attack.

The bomb killed 14 foreigners, including seven from China and Hong Kong, and wounded more than 100 people.

Investigators were trying to match the second detained man, who was arrested at the Thai-Cambodia border on Tuesday, with DNA left by the prime suspect in a cab, on fragments of the backpack and on a banknote given to a motorcycle taxi driver.

The man was carrying a Chinese passport which gave his name as Yusufu Mieraili, and his place of birth as the western Chinese region of Xinjiang, but it was unclear if it was authentic.

If the China link is proven it would add weight to theories by some security experts that the bombing could have been revenge by sympathizers of the mainly Turkic-speaking Uighur Muslims from Xinjiang.

Related: The Bangkok Bombing Was Planned and Executed by a 'Network,' Say Police

In July, Thailand deported 109 Uighurs to China, where many suffer persecution. That struck a chord in Turkey, which has a large Uighur diaspora.

Police have established a firmer Turkish connection, using the language to interrogate the suspects, one of whom was arrested with fake Turkish passports. Two other suspects are believed to be in Turkey.

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