The move indicates that investigators doubt key suspect Priyanuch Nonwangchai’s claim that the killing was accidental.

“There is evidence that the suspects made preparations for the murder,” Provincial Police Region 4 deputy commissioner Pol Maj-General Tanasak Rittidejpaiboon said yesterday.

Pol Maj-General Charoenwit Sriwanich also said police planned to conclude the investigation within 84 days and would object to any bail request during that period.

The gruesome crime took place last month in Khon Kaen province, with the victim’s body being cut into pieces and buried in a forest.

Priyanuch and two alleged accomplices, Kawita Rachada and Apiwan Satayabundit, fled to Myanmar following the crime but they surrendered to Myanmar authorities earlier this month and were deported to Thailand. Two other suspects, Wasin Namprom and Jidarat Promkhun, were arrested in Thailand. All but Jidarat face the additional premeditated murder charge.

Charoenwit said the additional charge was on top of other charges that had already been pressed against the suspects in connection with the murder.

The death penalty is the only punishment for defendants convicted of premeditated murder. If convicted of murder without premeditation, penalties range from jail terms to the death penalty.

Charoenwit added that authorities were also probing the suspects’ financial transactions and working with the Office of Narcotics Control Board (ONCB) to determine whether the suspects were involved in illicit drugs.

ONCB secretary-general Sirinya Sittichai said yesterday that Tawatchai Omchompoo, the man who helped the three suspects flee to Myanmar, was wanted in Thailand over drug allegations.

“He has fled to Myanmar while his drug case goes to the Appeals Court,” Sirinya said.

Sirinya said suspected traffickers who had fled from Thailand to Myanmar usually opened up businesses in Tachileik and nearby cities. Priyanuch and her two accomplices were known to have worked at a karaoke lounge in Tachileik for a few days before they surrendered.

Kawita’s elder sister denied widespread reports that Kawita had millions of baht in her bank account.

After visiting Kawita in jail, the sister also said Kawita insisted that she had just taken a ride with her friends and did not know it would implicate her in a crime.

Meanwhile, two immigration police officers in Chiang Rai province have been transferred out of their posts for taking photos with a smiling Priyanuch after she was handed over by Myanmar officials.

They are also facing a probe over the photos and their conduct.