The Department of Special Investigation (DSI) on Thursday played down an accusation made by Chaiwat Limlikit-aksorn -- a key suspect in the murder of Karen activist Porlajee "Billy" Rakchongcharoen -- that fabricated DNA evidence is being used against him.
DSI director-general Pol Col Paisit Wongmuang declined to comment on Mr Chaiwat's claim although he insisted the DSI has obtained sufficient evidence before it secured arrest warrants for Mr Chaiwat and three other suspects.
On Monday, the Central Criminal Court for Corruption and Misconduct Cases issued arrest warrants for Mr Chaiwat, Bunthaen Butsarakham, Thanaset Chaemthet and Kritsanaphong Chitthet on suspicion of murdering Porlajee.
The following day, the four turned themselves in to the authorities to answer the charges and were then released on bail.
Mr Chaiwat on Wednesday gave a television interview, in which he accused an unnamed party of setting him up to get him arrested and prosecuted in the Porlajee case.
He also raised doubts over the authenticity of the DNA evidence used against him, which the DSI obtained five years after the disappearance of the Karen activist.
Pol Lt Col Wannaphong Khotcharak, director of Central Institute of Forensic Science, said the nine bone fragments believed to be Porlajee's were inspected using a mitochondrial DNA test that traces a person's matrilineal ancestry using the DNA in his or her mitochondria.
Results of another test to confirm the results of the preliminary DNA test are expected this week and will be forwarded to the DSI," he said.
Porlajee went missing in April 2014 while he was helping his relatives sue Mr Chaiwat for allegedly setting fire to their bamboo huts and rice barns during a series of forest evictions in Kaeng Krachan National Park.
Mr Chaiwat, then-chief of the park, and a number of park officials were charged with the man's disappearance, but were later acquitted due to lack of evidence.
However, in June, the DSI discovered skull fragments in an oil drum in the Kaeng Krachan reservoir.
After a DNA test was carried out, a murder investigation was immediately launched.
