Thai police said they consider the Aug 17 Erawan blast case solved, and awarded themselves big wads of cash in front of journalists.
The cash comprised donations from private businessmen as well as outgoing police chief General Somyot Poompunmuang's personal money, the chief said.
It was the second time "award'' money has been given to the police teams working on the case.
But while blaming a people-smuggling network for the deadly rush hour blast at a venerated shrine in downtown Bangkok, Gen Somyot left open the possibility of a domestic political angle as well.
At a press conference in Bangkok yesterday, Gen Somyot, who is serving his last days in office before retiring, reiterated that the bomb attack was revenge by a gang which was smuggling ethnic Uighurs out of China and had been damaged by a police crackdown.
But he said one of two Thai suspects in the case had also been involved in a bomb blast at an apartment in Nonthaburi on the outskirts of Bangkok in 2010.
"The (Erawan) bombing was a retribution for the government crackdown on human smuggling. And we also believe that there is a person or group, who hired this group. The police will investigate further,'' Gen Somyot said.
"We have yet to establish these (political) links. It might have been a contract crime. A group might have hired another already bent on taking revenge to commit the crime so both got what they wanted,'' he said.
One of the Thai suspects, identified as Aod Payungwong or Yongyuth Pobkaew, had previously been involved in "political bombings" in 2010 and last year, Gen Somyot said.
The suspect had been involved in the explosion in the Nonthaburi apartment building in October 2010 which killed four people, including a man while he was probably assembling a bomb, the police said at the time.
Then, the government blamed the Nonthaburi blast on former premier Thaksin Shinawatra's "red shirts'' supporters who, earlier that year, had been dispersed from entrenched protest sites in Bangkok by an army crackdown.
The Aug 17 blast at Erawan shrine was the deadliest in memory in Thailand, killing 20 people, including 12 foreigners.
The police have issued at least 17 arrest warrants, including for Chinese and Pakistani nationals, and have two people in custody. Both men - Adem Karadag and Mieraili Yusufu - have confessed to the attack.
Over the weekend, they said Adem Karadag, also known as Bilal Mohammed, whose nationality is still unclear, had confessed to actually planting the bomb at the popular shrine.
The police had interviewed more than 200 witnesses and reviewed closed-circuit television (CCTV) footage in connection with the blast, the police chief said. In connection with a second blast the next day in which nobody was hurt, the police had interviewed 30 witnesses and also examined CCTV footage.
There were two groups of perpetrators, of nine and seven people, respectively, staying at two different apartment blocks in Bangkok's Minburi district, Gen Somyot said.
"These two groups had different duties but they are the same network,'' he said.