The Department of Special Investigation (DSI) says its probe into the alleged murder of Karen forest activist Porlajee "Billy" Rakchongcharoen will not be derailed after recent DNA tests on more bone fragments came up blank.
Nine pieces of bone were examined and were not linked genetically to skull fragments retrieved earlier which were tested and proved a match with Porlajee's DNA, according to authorities.
The nine pieces and Porlajee's skull fragments were retrieved from Kaeng Krachan reservoir in Phetchaburi earlier this year. The nine other bone pieces were found 10 metres from the spot where an oil drum was discovered containing Porlajee's skull fragments.
DSI chief Paisit Wongmuang insisted the test results would not slow the momentum of the Porlajee murder investigation.
An earlier examination found genetic traces of the skull fragments taken from the oil drum matched that of Porlajee's mother, a discovery that led the DSI to assume they belonged to Porlajee who is believed to have been murdered.
A source close to the investigation said the DSI has ruled out the possibility of the skull pieces coming from another of Porlajee's relatives.
The investigators will ask forensic experts to positively identify the differences between the skull fragments and the nine other bone pieces for the sake of clarity.
Initial findings confirmed the nine other pieces had been burned.
Porlajee disappeared in April 2014 while he was helping relatives sue former Kaeng Krachan National Park chief Chaiwat Limlikit-aksron for setting fire to their bamboo huts during a series of forest evictions.
Mr Chaiwat, now head of the Ubon Ratchathani-based Protected Area Regional Office 9, and three other suspects are charged with involvement in the murder.
He admitted to having arrested the activist for collecting wild honey but claimed he released him after issuing him a warning.
Mr Chaiwat and his aides reportedly failed to disclose when and where they released Porlajee.
