A committee has been set up to investigate a group of police officers at Thong Lor station in the city over their handling of a 2012 hit-and-run involving an heir to the Red Bull energy drink empire, acting city police chief Pol Lt Gen Sanit Mahathaworn says.
The Thong Lor police station was responsible for handling the case involving Vorayudh "Boss" Yoovidhya, who drove into and killed a traffic officer, and was subsequently charged with speeding, reckless driving causing death and failing to stop his car to help a victim after the crash.
Pol Lt Gen Sanit said the inquiry is in line with Section 131 of the Criminal Code that requires investigators to gather evidence and build a case without delay.
The inquiry will focus on why Mr Vorayudh could not be indicted before the one-year statute of limitations on his speeding charge expired in 2013.
Of the three charges, the speeding charge, expired after Mr Vorayudh failed to report to prosecutors.
The suspect's 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.
Pol Lt Gen Sanit said if the police had done their job properly, Mr Vorayudh would not have been allowed to leave the country.
In a criminal investigation where a victim is killed, police usually seek a court order to detain the suspect who, if granted bail, will be barred from travelling abroad, according to the acting commissioner.
He said the investigators responsible for the case might have used a technicality to avoid seeking a court order for the suspect's detention.
Pol Lt Gen Sanit said the suspect apparently exploited a technicality to drag out the investigation by lodging a petition with Attorney-General Chulasingh Vasantasingh to seek a fair investigation.
Mr Vorayudh submitted six separate petitions, all of which were granted.
Police investigators initially charged Mr Vorayudh with reckless driving causing death and failing to stop his car to help a victim, before forwarding the case to state prosecutors.
However, the case was sent back to the police as prosecutors also wanted to indict him for speeding after security camera footage showed he may have been driving at up to 170kph when the accident took place.
The acting commissioner was also critical of the police's decision not to charge Mr Vorayudh with drink-driving, a charge that has a statute of limitations of five years.
Meanwhile, Orachorn "Praewa" Thephasadin na Ayudhya, who also hails from a wealthy family, and caused an expressway crash that killed nine people in 2010, has applied to do more community service at Phramongkutklao Hospital.
The court is currently deciding whether her performing the community service there should count towards her parole time.
Ms Orachorn, who was 16 years old when the crash happened, and not even eligible to hold a licence at the time, was eventually found guilty of reckless driving causing death, although her prison sentence was suspended.
Ms Orachorn is required to do 48 hours of community service a year for four years, a condition she must meet to avoid jail time.