Police investigation into the murder of Britons Hannah Victoria Witheridge and David William Miller on Koh Tao off the Surat Thani coast appears to be mired in flaws - some from outside factors and some from investigators' own mistakes.
One of the biggest flaws was when investigators wasted a lot of precious time by initially focusing their efforts on interrogating migrant workers and combing their accommodations - a move that many put down to racial bias.
The other key setback - perhaps the most vital one - was the police force's unsophisticated forensic technology and carelessness at the crime scene.
Later, the shifting of focus from migrant workers to tourists and Thai residents, including bar owners and their staff, also proved to be fruitless, turning up no new substantial clues or leads.
Also, initial theories - that the male victim and his male travel companion were close and that the killing may have been the result of jealousy - proved to be groundless. In addition, the victims' fellow travellers have all returned home.
Now the police are under extra pressure as the international media have started attacking them for what they call aimless efforts that have turned up no clues after nearly two weeks since the killings.
Some of these setbacks, however, cannot be solely blamed on the police. For instance, daily high and low tides have been washing away evidence on the beach and investigation personnel lost time while trying to get to the far-flung island.
Also, before local police officers arrived at the crime scene at dawn on September 15, many locals had already messed up the evidence by moving the two murder weapons - a hoe and a wooden stick - and thereby affecting the fingerprints. Then there's the problem of finding the people whose DNA has been discovered on cigarette butts and looking to see if they have any links to the murders.
Then there's the most puzzling piece of evidence only made public for the first time on Wednesday by deputy national police chief Pol General Somyot Poompanmoung - a condom found in the area that had Witheridge's DNA on the outside but nothing on the inside.
Then there's her mobile phone, which has gone missing.
Thai police are reportedly coordinating with her family in the United Kingdom to get phone registration details and see if they can unearth any relevant clues.
In addition to this, the Thai Institute of Forensic Medicine's inability to verify the DNA and narrow it down to race, hair and skin colour has certainly slowed down scientific evidence, which is crucial in such mysterious killings.
Police initially thought of turning to the US Federal Bureau of Investigation for help, but the idea was dropped when getting similar assistance from Singapore became an option.