After weeks of demurring, Thailand has suggested that those behind the blast may have been from a gang involved in smuggling Uighurs

A key suspect in last month’s bombing at a Bangkok shrine that killed 20 people has fled to Turkey, Thai police said on Monday, in another indication that the attack could be the work of members of China’s ethnic Uighur minority who have sympathizers in Turkey.

Police had previously said the man, carrying a Chinese passport in the name Abudureheman Abudusataer, may have directed the Aug. 17 bombing of the Erawan Shrine. Investigations revealed that he left Thailand on Aug. 16 for Bangladesh, and police speculated that he might have gone to China.

“He departed Dhaka on Aug. 30 for Delhi by Jet Airways,” Prawut said. “From Delhi, he continued his travel to Abu Dhabi, and from Abu Dhabi he travelled on Aug. 31 to Istanbul. This is his final destination. It’s clear.”

This bolstered the theory that those behind the blast are Uighurs (pronounced WEE—gurs) from the Chinese region of Xinjiang who have close ties to Turkey. Several of the 12 bombing suspects for whom arrest warrants have been issued are believed to be Turkish.

After weeks of demurring, Thailand has suggested that those behind the blast may have been from a gang involved in smuggling Uighurs. But others speculate they may be separatists or Islamist extremists angry that Thailand repatriated more than 100 Uighurs to China in July.

Uighurs complain of oppression by the Chinese government, and some advocate turning Xinjiang into a separate Uighur state.

Thai efforts to identify the members of the network believed responsible for the bombing continued on Sunday, when police in Bangkok raided an apartment that they suspected was linked to a bombing suspect. Police said no bomb-making materials were found in the apartment, which is in a building that serves as a hostel for women. Thai media reported that the two women tenants and a guest were taken away for questioning.

Two other key suspects are also in custody, charged with possession of illegal explosives. One of them was captured from an apartment on the outskirts of Bangkok where police also discovered bomb-making material. The other was caught near the border between Thailand and Cambodia, and police said his fingerprints were found on a container with explosive material confiscated from the apartment.

Also on Monday, Malaysia’s police chief announced that a Pakistani and two Malaysians have been detained in connection with the Bangkok bombing.

Inspector General Khalid Abu Bakar told reporters that the three were detained a few days ago following a tip-off by Thai authorities. He said one of the Malaysians is a woman.

Among those who died in the blast were five Malaysians from one family. Many of the victims were foreigners as the shrine is a popular destination for tourists and Thais alike.

Mr. Khalid did not give details or say where in Malaysia the three were detained, when they will be formally charged, or what the charges would be. He said Malaysian police will investigate and work with Thai authorities on the detainees.

Thai police say the man who may have actually planted the bomb may have fled across Thailand’s southern border to Malaysia, but Mr. Khalid refused to speculate on that.

Mr. Prawut, the Thai police spokesman, said his department had told the Malaysians that some suspects might have escaped to Malaysia.

Malaysian police then investigated and arrested suspects who are allegedly involved in illegal human smuggling and they might have some information, Mr. Prawut said.

“However, we haven’t had any confirmation. ... As a preliminary step, they have arrested suspects who are allegedly involved in illegal human smuggling. Whether they are involved in our bombing incident or not we will have to wait and see,” he said.