Police chief Somyot Pumpunmuang has transferred the investigation into billionaire Chuwong Sae Tang's death and share transfers away from Bangkok police and the Crime Suppression Division to police headquarters, to prevent "unfair influence".
"The case was transferred to the Royal Thai Police Office because I want it to be treated fairly, free from accusations and handled by senior executives of the Royal Thai Police Office. I heard that someone tried to influence the case with personal power and money," Pol Gen Somyot said on Monday.
His decision followed a request by Chuwong's family to transfer the investigation into the "accident" in which the billionaire was found dead to the Crime Suppression Division.
Bangkok's Udomsuk police station earlier handled the accident investigation and the CSD was probing the transfers of Chuwong's shares worth about 260 million baht to two women who claimed to be his mistresses just before his death.
Pol Gen Somyot said assistant national police chief Prawut Tavornsiri would have responsibility for the investigation into both the death and the share transfers.
"Pol Lt Gen Prawut will set up a special investigation panel of the Royal Thai Police Office. Capable interrogators will be selected to handle the task," the police chief said.
He also said that he might later assign Pol Gen Jarumporn Suramanee, adviser to the police chief, to closely handle the case.
On Monday an elder sister and a son of Chuwong asked Khunying Pornthip Rojanasunan, director-general of the Central Institute of Forensic Science, to look into the possible cause of Chuwong's death as they had suspicions about inconsistent reports about injuries found on his head.
Khunying Porntip told them to gather information from the doctor who examined Chuwong's body and seek permission from the Justice Ministry or the Department of Special Investigation to let her central institute participate in the investigation.
She also said that if Chuwong had an injury to the back of his head, that would be irrelevant to the possibility he died in a head-on crash involving the vehicle he travelled in.
The forensic specialist added that Chuwong's family was waiting for the arrival of a 10-million-baht crash dummy from overseas to help prove the cause of death.
Chuwong, 50, the owner of the large construction firm Standard Performance, was found dead in the front passenger seat of a Lexus sport utility vehicle that had a minor accident with a roadside tree in Prawet district, Bangkok, on June 26, 2015.
Former deputy commerce minister Banyin Tangpakorn was the driver. The two men first met during a course at the National Defence College a few years ago.
Chuwong's family also questioned the transfer of hundreds of millions of baht of his shares to two young women who claimed to be his mistresses, in June, just before the accident. One of the women reportedly used Pol Lt Col Banyin's phone to contact Chuwong.
One of the women, Kanthana Siwathanapol, 26, who used to work as caddie at Chuwong's golf club and as a model, returned to the Crime Suppression Division on Monday for further questioning. She said that she had not expected the huge share transfer of 228 million baht of shares from Chuwong, but he said he intended the shares to ensure her security.
Ms Kanthana claims to be eight months pregnant by Chuwong. Her lawyer, Seksan Senachoo, said tests had already been made on a DNA sample from the unborn child, but would not reveal the result.
The lawyer said the DNA matter had nothing to do with the investigation into the share transfer.
He admitted his client had a relationship with a son of a deputy governor of Surat Thani province, but said it had ended before she began her relationship with Chuwong.
Mr Seksan denied that Chuwong knew the man, or the man who took Ms Kanthana to Siriraj Hospital in Bangkok for prenatal care.
The second woman who also claimed to be Chuwong's mistress and received a large transfer of shares to her name, share broker Uracha Wachirakulton, 26, was due to report to the CSD on Tuesday afternoon.