Surat Thani-based public prosecutors yesterday returned the police's investigation report into the murder of two British tourists last month to the officers that had produced it, asking them to supply "more crucial information".
Describing the killings "as high profile, attracting attention from society around the world", the prosecutors reportedly also told the police to "fix certain flaws" and make the 850-page report "more succinct", without giving them a time frame in which to do so.
Meanwhile, Parinya Sirisarakarn, a member of the National Human Rights Commission (NHRC), yesterday gave new information about forensic evidence and claims made by the two suspects - Maung Saw and Maung Win - whom he had met.
He said they told him they had not used condoms while sexually violating the female victim, contrary to earlier police statements that sperm carrying their DNA was found on the outside of condoms.
Parinya also said a Rohingya interpreter was used during the police interrogation of the two suspects, who are from Rakhine state, who allegedly bore a grudge against Rohingya people, apart from their different languages.
He added that both suspects bore wounds as a result of what they claimed was "the police not treating them properly".
"However, both suspects insisted [to me] that they had committed the crimes," said the human-rights commissioner.
Prime Minister Prayut Chan-o-cha yesterday called on the Thai public and media not to specifically mention the nationality of the suspects, and suggested that they be referred to instead as "migrant workers", after news reports in global media specified the suspects as the nationals of a neighbouring country all along.
"I need to ask the Thai media for cooperation on this," he added.
The NHRC and Myanmar Embassy officials are jointly interviewing Myanmar migrant workers on Koh Tao while collecting general information.
Most of the workers reportedly say they do not believe that the suspects are the real killers, and that there must be some motive behind their having admitted to the murders.
Thai and foreign tourists are travelling in greater numbers to Koh Tao and nearby Kon Samui and Pha Ngan in the wake of the Full Moon Party last night on Pha Ngan, resulting in two extra ferry trips to accommodate them.
Bunsiri Deowanich, the manager of a ferry company, said there had been a 20-per-cent drop in visitor numbers to Koh Tao prior to the arrests of the two suspects.
A source said that personnel from the provincial port authorities were stationed at all piers to ensure extra security and handle any possible emergency.
Some 90 per cent of the roughly 15,000 rooms on Koh Tao have been occupied, and around Bt100 million would be spent last night on Full Moon events alone, said the source.