Pressure on the Office of Attorney-General (OAG) is mounting as many groups, including constitutional bodies, demand an explanation for its decision to drop all charges against Red Bull scion Vorayuth Yoovidhya.
While the OAG remains silent, a lawyer who claimed he saw the document detailing the prosecutors' reasons said the decision was a result of the testimony of two witnesses who said the killed policeman abruptly changed lane on his motorcycle, thereby causing the fatal hit-and-run incident in 2012.
This week, news broke that the OAG had in June dropped a reckless driving causing death charge against Mr Vorayuth, who had fled the country, despite the statute of limitations for the charge not expiring until 2027.
Thammasat University vice-rector and law lecturer Prinya Thaewanarumitkul on Saturday stressed that both the OAG and the police owe the public an explanation.
"Don't let the case confirm public suspicions that the justice administration system can be rigged. The police also owe the public an explanation as to why they did not challenge the decision," he said.
Democrat deputy leader Nipit Intarasombat posted on Facebook that the controversy could snowball and ultimately undermine the government itself.
"This matter is very serious and the prime minister, the attorney-general and the chief of police will have to address the public. Even though it doesn't directly involve the premier, he can't sit idly by," he said.
With public anger escalating, at least three bodies have signalled their intention to take action over the matter.
Activist lawyer Songkan Atchariyasap said he will bring the matter before the national reform committee on police affairs, of which he is a member, next week. Two former attorneys-general, Khemchai Chutiwong and Trakul Winitchaiphak, serve on the panel.
Rewat Wisarutvej, a list-MP of the Seriruamthai Party and a member of the House panel on justice administration affairs, said the panel will look into the case and summon the attorney-general to clarify the matter.
"The case is telling the people there are double standards in the system," he said.
And Pol Gen Sereepisuth Temeeyaves, chief of the House anti-graft committee said if someone filed a complaint, his committee would also look into the matter.
Meanwhile, Attorney-General Wongsakul Kittipromwong has distanced himself from the furore.
Prayuth Petchkhun, deputy spokesman of the OAG, said Mr Wongsakul, who is upcountry for an inspection trip and will not return until next week had only learned of the decision himself from media coverage.
According to Mr Prayuth, the attorney-general will not comment until he has examined the details.
Mr Prayuth said that for cases in Bangkok if the decision to drop the charges is not made by the attorney-general, the case must be forwarded to the national police for consideration. If the police chief agrees with the decision, the case is finalised.
Decha Kittivittayanan, founder of the Tanai Klai Took (Lawyers Relieve Suffering) Facebook page, said he had seen a document showing the reasons behind the prosecution's decision to drop the charges against Mr Vorayuth who is accused of being behind the wheel when his Ferrari hit and killed Pol Sgt Maj Wichian Klanprasert, a motorcycle policeman, on Sukhumvit Road in Bangkok, on Sept 3, 2012.
He said two more witnesses had been identified from security camera footage. Both of them said they were driving behind Mr Vorayuth who was driving under the 60 km/h limit in the third lane, while the police officer, who was in the left lane, suddenly cut in front of his Ferrari.
Previously, forensic police had concluded that Mr Vorayuth had been driving at 177 km/h.
The National Anti-Corruption Commission in June revealed that it found there had been an intention by police to exempt Mr Vorayuth, now aged 35, from prosecution on charges of drug abuse and speeding despite the forensic result and a blood test.
