Maj. Gen. Paween Pongsirin told CNN by phone from Melbourne, Australia, that members of Thailand's political and business elite -- including one general in the country's armed forces -- had called him to ask that he stop the investigation. He said he wasn't able to say how many death threats he had received.
Paween was appointed to be chief investigator of a suspected Rohingya trafficking network after at least 30 graves, believed to contain the bodies of trafficked Rohingya, were discovered in May in the southern part of Thailand.
The Rohingya, a long-oppressed linguistic and ethnic minority in Myanmar, began to flee the country after clashes with the Rakhine state's Buddhist community in 2012. The United Nations estimates more than 100,000 Rohingya have fled Myanmar since the ethnic and sectarian violence erupted. Some said they were forced to leave by men who threatened to beat them.
Those who had the means to leave did so by perilous sea journey. They were taken out on small boats to cargo ships by smugglers, mostly bound for Malaysia. However, once on the open water, many neighboring countries refused to take them in.
At the peak of the investigation into the suspected Rohingya trafficking network, Paween led about 80 police investigators on the case. However, after handing evidence to the public prosecutor, he was reassigned to a remote southern region of Thailand. Police maintain they thought his investigative skills could be put to better use in the region, but Paween quit the force soon after the reassignment, in November.
High-ranking officials on trial
The trial for 88 suspected human traffickers, including government figures, civilians, police and military officers -- among them, Lt. Gen. Manas Kongpan, a special adviser to the Royal Thai Army -- will begin next March. Manas, the highest-ranking official to be implicated, has denied the charges in media reports and vowed to fight them.
Brad Adams, the executive director of Human Rights Watch's Asia division, said earlier this year that Rohingya refugees described in interviews "how they flee persecution in (Myanmar) only to fall into the hands of traffickers and extortionists, in many cases witnessing deaths and suffering abuse and hunger.
"Interviews with officials and others make clear that these brutal networks, with the complicity of government officials in Burma, Bangladesh, Thailand, and Malaysia, profit from the desperation and misery of some of the world's most persecuted and neglected people," Adams added.
Paween said there were many institutional efforts to block his investigation. On one occasion, he said, he requested the financial transactions of suspects including Manas, but his superior, whose name he was unwilling to divulge to CNN, blocked his request. In an interview with CNN, police spokesman Gen. Sutticharnbancha said there was no effort to block Paween's investigation.
Paween arrived in Australia several days ago on a tourist visa via Singapore, and said he planned to seek asylum. Before that, he'd been preparing for the trial with prosecutors and defense lawyers when his supervisor told him to "resign and stay silent." That triggered his flight to Australia.
Sutticharnbancha denied Paween's assertion that he was told to resign. "As far as I know, (Paween) has resigned from the Royal Thai Police, so he has the right to go anywhere or do anything. I have just learned about his application for asylum in Australia from news. So (I) don't have comments on that."
'Honest and experienced investigator'
Paween was known as "a no-nonsense straight shooter, really an honest and experienced investigator -- so many people were pleased when he was appointed to head the investigation of the trafficking of the Rohingya boat people because it seemed to indicate that Thailand was determined to ensure accountability for these serious crimes," Phil Robertson, deputy director of Human Rights Watch's Asia division, told CNN via email.
"Successfully resolving this situation is a major test case for Thailand's commitment to fulfill its promises to eradicate human trafficking. If Paween fears for his life, imagine how the Rohingya witnesses to these crimes are feeling today -- so quite clearly their safety also needs to be a top priority."
Paween said he hadn't planned his escape before leaving Bangkok and as a result finds himself in Australia with little money and facing a lengthy asylum application process.
A spokesperson for Australia's Department of Immigration and Border Protection declined to comment on individual cases due to privacy reasons.
"All claims for protection are assessed on their individual merits in accordance with Australia's domestic legislation and obligations under international treaties and the Refugees Convention," the spokesperson said.