Metropolitan Police Bureau (MPB) chief Khamronwit Thoopkrajang has affirmed the murder of businessman Akeyuth Anchanbutr was motivated by money.
"Every piece of evidence we have points to robbery and murder," Pol Lt Gen Khamronwit said after meeting the investigators working on the billionaire's homicide case yesterday.
"The police welcome any new information that might come to hand," he added.
The police have been on the case for three weeks.
Pol Lt Gen Khamronwit stressed there was no political motive behind Akeyuth's killing. His insistence comes amid assertions by Akeyuth's lawyer, Suwat Apaipak, who has said there is more to the case than meets the eye.
Pol Lt Gen Khamronwit said the police have pursued the case with utmost care and questioned 51 witnesses so far.
Police will also invite Mr Suwat to hear the investigators' explanation, he said.
Mr Suwat earlier submitted a list of 13 questions about the case which he said remained unanswered. He said he wanted the police to address the queries before wrapping up the investigation.
Pol Lt Gen Khamronwit said all those questions have now been answered.
Police have not found Akeyuth's valuables, which disappeared during his abduction and murder, he said.
The billionaire's driver, Santiphap Pengduang, 24, has been accused of killing his boss. He is alleged to have conspired with Sutthipong Pimpisarn, 27, and three others to murder Akeyuth and steal 5 million baht from him.
Two other suspects have also been charged in connection with the murder. They are Chaowalit Woonchum and Thiwakorn Kuathong.
Investigators say Akeyuth was murdered during a drive from Lat Krabang in suburban Bangkok to the South.
Pol Maj Gen Supisal Pakdinaruenart, commander of the Crime Suppression Division, said Mr Santiphap was aggressive and addicted to gambling. Police have recovered a gun, a knife and shackles from the suspects, he said. Pol Maj Gen Supisal insisted Mr Santiphap and Mr Suthipong were the killers and were intent on stealing Akeyuth's valuables.