Bangkok, Thailand - Zaw Lin and Win Zan Htun stepped out of a caged truck on November 20 and entered Thailand's Koh Samui provincial court.

Suspected of the grisly murders of British tourists Hannah Witheridge and David Miller, the migrant workers from Myanmar had yet to be charged some 48 days after their arrest.

I met with them every two days. I'm very suspicious that they could do something like that. - Andy Hall, l abour rights activist

The killings on Koh Tao (Turtle Island), a small, rocky island that has become increasingly popular with young travellers, have sparked a wave of international press coverage and online speculation.

As prosecutors implored the judge to extend the pre-charge detention for the fifth time, the shackled pair, both 21, resembled little more than overawed schoolboys.

During breaks, they spoke with journalists and NGO workers, reiterating their innocence as their lawyer - futilely - urged their release.

"I'm not surprised [the release was denied]," defence lawyer Nakhon Chompuchart told Al Jazeera after the judge granted another extension. "It's the common thing. It would be surprising if they got out."

A week later, the pair was denied bail, surprising Myanmar officials who were expecting the pair to be released.

Nakhon said he was "positive" the men are innocent. " The police have no evidence. "

The suspects

On the morning of September 15, the bodies of Witheridge, 23, and Miller, 24, were discovered on a stretch of Koh Tao beach. Both victims had been bludgeoned by a hoe. Miller had drowned during the attack and Witheridge was believed to have been raped.

In spite of the severity of the crime, the police probe has appeared farcical to many, and has even drawn criticism from within the ranks of Thai investigators . The beach was not cordoned off, and the crime scene was immediately contaminated.

Some say possible suspects were permitted to leave Koh Tao, while the police fingered the migrant workers before spinning an elaborate "love triangle" story implicating another tourist. When they were forced to abandon that path, they investigated different lines before settling back on migrant workers.

Zaw Lin and Win Zan Htun were arrested on October 3, and their confessions were quickly disseminated to the press. When the pair retracted their statements two weeks later, saying they had been tortured while in police custody, it simply added ammunition to claims of police incompetence or, worse, a cover-up.

"Our suspicion is that maybe the investigation process is not adequate. Maybe they focused on the wrong thing," said Andy Hall, a labour rights activist who has been observing the case. "It's quite common for migrants to be systematically abused, extorted by officials.

"I met with them every two days. I'm very suspicious that they could do something like that."

Social media maelstrom

Few cases have captured international attention like that of the murders on the idyllic Thai diving island. In Britain, Thailand, and farther afield, every twist has been captured in tabloids and more sternly documented in the broadsheets.

While news media have stirred public interest, the internet has sent it into frenzy. That's true nowhere more so than inside Thailand, where an unprecedented level of social media engagement in the case has forced several turnabouts in the investigation.

A British policeman and Thai officers inspect the murder scene [EPA]

At the epicentre of the social media maelstrom lays CSI LA, a Facebook page run by an amateur forensicist that has garnered half-a-million followers - avid armchair detectives whose speculation has forced rare high-level public concessions.

"Because of my effort and our community effort, we were able to gather 100,000 signatures for the petition [calling for a UK police probe]," said David Anantasin, the Thai California resident behind the page.

"I use the concept of crowd sourcing. I utilise people's brains," he told Al Jazeera in a Skype interview.

While police are adamant they nabbed the killers, the internet gumshoes favour a different suspect: the son of a wealthy and influential Koh Tao village headman.

Netizens have speculated that alibi-providing CCTV footage was faked, the headman's son was spirited away to avoid a DNA test, and the highest levels of government are covering for a powerful island mafia. By late October, the outcry had grown so loud the village headman's son voluntarily turned himself in for DNA testing at four separate institutions.

As the tests were carried out, police issued a stern warning.

"Posting or commenting on social media may seem like a lot of fun ," Major General Paween Pongsirin told Phuket News, "but it is not so much fun when you are summoned by police to answer criminal charges."

Bilateral mess

Such threats, however, have fallen on deaf ears and the outpouring of criticism has put Thailand's Prime Minister Prayuth Chan-ocha in a harsh limelight.

"Surely Prayuth has mishandled the case... The aim perhaps [was] to protect the tourism industry but not telling the truth cost Prayuth more than he could imagine," said Pavin Chachavalpongpun, an exiled Thai political analyst at Kyoto University in Japan.

All of the evidence has shown that these suspects have done this crime… DNA is very strong evidence, and our standards have followed the protocol of investigation. - Lieutenant Colonel Sunshine Ratanatanata

The general, who came to power after the May 22 military coup, has struggled to gain legitimacy on a global stage. While the suspect investigation has hardly helped his cause, his personal role has drawn particular ire.

Just days after the killings, Prayuth garnered international condemnation when he suggested first that the "behaviour" of the victims must be investigated, and later that women "in bikinis" could not be expected to be safe "unless they are not beautiful".

Two weeks later, after claiming the UK was happy with the Thai investigation, he was forced to backtrack and permit Scotland Yard to carry out its own inquiry.

Avoiding the usual diplomatic channels, the UK's Foreign Office issued a statement saying Minister Hugo Swire "stressed that there was a real concern in the UK about how the investigation has been handled by the Thai authorities".

'Perfect job'

The police have repeatedly defended the investigation. Last month Police Chief Somyot Pumpunmuang told journalists they had done "a perfect job".

Lieutenant Colonel Sunshine Ratanatanata, a deputy police spokeswoman, also told Al Jazeera that police were confident about the investigation, and that British investigators, who wrapped up their visit earlier this month, had praised Thai police for their assistance.

"All of the evidence has shown that these suspects have done this crime ... DNA is very strong evidence, and our standards have followed the protocol of investigation," she said.

Regardless of the quality of investigation going forward, it is clear the damage is done.

David Streckfuss, an independent Thailand-based analyst, called it a "public relations fiasco" for a nascent military government struggling to gain legitimacy.

"Because foreigners are involved, it gets more airtime. But [the case] is emblematic of the deeper, more domestic focused problems like suppression of human rights," he said.

"Thailand's public relations effort under dictatorship has not been very good. The regime has been desperate to gain acknowledgement in any way it can from whoever it can. But the reality behind the image is that Thailand is in distress."