Police have arrested hundreds of Islamist militants, spoken to 150 witnesses and circulated photographs of the bombers' severed heads, so far without a breakthrough. After the terrorist bombings on the island in 2002, one vital clue, and diligent detective work, set police on the bombers' trail within hours. Progress is slower this time.
The suicide bombing, which killed four Australians and a Japanese tourist, represented a change of tactics for extremists in the world's most populous Muslim nation. The attack at Kuta Beach three years ago, which claimed 202 lives, was costly and complex. After a bomber detonated explosives in his backpack at Paddy's Bar, a nightclub, a massive bomb went off in a van outside the nearby Sari Club. The latest strike was less devastating, but easier to accomplish. All it required was explosives, some bomb-making capability and three men willing to lay down their lives. The impoverished villages of rural Indonesia are teeming with the latter, many of them indoctrinated in religious boarding schools. And Bali is full of soft targets.
Suspicion has fallen on Jemaah Islamiyah (JI), the extremist group that originated in Indonesia and whose senior operatives helped to plan the October 2002 blasts. But last week's attacks on three restaurants - one in Kuta, two in Jimbaran, another tourist enclave - could have been carried out by an autonomous cell. The bombers are believed to have visited each restaurant on the afternoon of the blasts, accompanied by a woman, and to have asked staff what was their busiest time.
Some regional terrorism experts say the operation's relatively low cost and simplicity demonstrates that JI is fragmented and short of funds. Others say it shows the group'scontinuing ability to sow fear and mayhem. The bombers had no police records and have not been recognised by anyone, including jailed JI operatives, which suggests they were fresh recruits. The Bali police chief, Made Mangku Pastika, said they were probably enlisted specifically for last weekend's attacks.
More than 300 members of JI, including Hambali, a senior al-Qa'ida link man, have been detained across South-east Asia since the Sari Club blast. But several key figures are still at large, including two Malaysians suspected of orchestrating the latest atrocity: Azahari bin Husin, a bomb-maker, and Noordin Mohamed Top, a fundraiser and recruiter.
On Friday police raided a a village in central Java where Noordin was believed to have been hiding, but said later they had missed him by hours.Neighbours cast doubt on the claim, saying the man in question was Javanese and left a week ago. Investigators believe Noordin was in Bali before the bombings and then returned to the village. They are also trying to trace calls made to Balinese numbers by the wife of another suspect, Zulkarnaen, three days before the attacks.
Police helicopters have dropped thousands of photographs of Azahari and Noordin on villages across central Java, asking the public to report on their whereabouts. Some observers suggest that the pair may have acted under their own steam.
But as surfers held a sunset memorial ceremony on Jimbaran Beach last night, police were planning to increase security across the island before Wednesday, the third anniversary of the Sari Club bombing.