Almost a week on since the deadly Bangkok bomb attack, national police chief Somyot Pumpunmuang said investigators need some luck to catch those behind it, and they have already left the country.
Pol Gen Somyot was speaking to reporters early Sunday morning after a ceremonial show of security strength meant in part to reassure the public over safety.
"We need some luck. If the police have good fortune we might be able to make an arrest but ... if the perpetrator has good fortune maybe they can get away, " the police chief said.
The bombing on Monday at a popular city shrine left 20 people dead and more than 100 wounded. So far the operation to find who carried out the attack appears to have made little headway with apparently contradictory statements coming from the military-backed government and the police.
Police spokesman Prawut Thawornsiri said he believes the perpetrator would have timed an escape carefully and "wouldn't have much time to stay around."
"I suspect that he may have left, but we will keep searching, in case we can find others who may be in the country or find clues, evidence and witnesses who may have seen him," Pol Lt Gen Prawut said.