National police chief Chakthip Chaijinda has ordered Thong Lor police to clarify why the handling of a speeding charge against the heir to the Red Bull energy drink empire was so slow that the statute of limitations on it expired.
Pol Gen Chakthip said the public has a right to know what was slowing the probe at the station, which was responsible for the hit-and-run case involving Vorayudh "Boss" Yoovidhya in 2012.
Mr Vorayudh faced three charges in connection with the fatal incident, in which Pol Snr Sgt Maj Wichian Klanprasert, a Thong Lor station traffic officer, was killed. However, the speeding charge was dropped because the one-year statute of limitations expired.
The suspect is still wanted on two other charges -- reckless driving causing death and failing to stop his car to help a victim, which have a statute of limitations of 15 years and five years respectively. However, he has reportedly fled the country.
Pol Gen Chakthip said he did not believe police investigators deliberately dragged their feet over the case.
"There are steps involved when police work on a case. We have to find out which one of these steps is causing the delay. If it gets stuck at the prosecution stage, it is [their responsibility]. If it gets bogged down at the police investigation stage, we need to speed things up," he said.
Pol Gen Chakthip said if police are found to be negligent they will face disciplinary action. Initially, police investigators agreed to charge Mr Vorayudh with reckless driving causing death and failing to stop his car to help a victim.
However, the prosecution wanted to indict him with speeding as footage from security cameras suggested he might have been driving at up to 170km/hr when the accident took place. The case was sent back to police to gather more evidence.
Mr Vorayudh contested the prosecution and asked that police question six witnesses.
The Office of Attorney-General approved his request, which delayed the indictment by almost six months.
The prosecution planned to indict the suspect on Sept 2, 2013, one day after the statute of limitations on the speeding charge expired.
However, Mr Vorayudh failed to show up, and his lawyer, Thanit Buakhiew, claimed his client could not attend because he was in Singapore on a business trip and had come down with the flu.