In a shocking incident that exposed a chilling police-mafia alliance, a group of officers watched a fellow cop gunned down by a gang without intervening.
If that was not enough, six of the more than 20 police at the scene then helped the criminals escape and destroyed the evidence. Another six helped take the mortally wounded cop to hospital. The rest simply ran from the crime scene.
The killing, and how the policemen at the scene behaved, sheds light on why efforts to eradicate illegal businesses and the underground economy have failed repeatedly.
On Sept 6, the officers gathered for dinner at the house of Praween Chanklai, 35, a local godfather known as "Kamnan Nok" and the sub-district head of tambon Thakong in Nakhon Pathom.
Among them was Pol Maj Sivakorn Saibua, 32, a local highway police station chief accompanying his superior. Sivakorn had just been sent from Bangkok headquarters to tackle the "bribe stickers" that allow overloaded trucks to operate freely on highways. During the party, Mr Praween argued with Sivakorn, before his aide shot Sivakorn in front of everyone.
In the ensuing chaos, Mr Praween and the gunman fled in a car with a police escort. Blood at the scene was cleaned up, the gun was hidden, the security camera removed, and the computer server thrown into a canal.
Amid a public uproar, Mr Praween was arrested and denied bail, the gunman was killed extrajudicially and Sivakorn's superior committed suicide. Hidden evidence such as the CCTV camera and pistol have been retrieved.
The latest developments have the media and public attention focusing on Mr Praween's business, while police have now declared war against local gangsters. The question is though, what will police do with the gangsters in police uniforms?
Corrupt policemen are often described as a few rotten apples. The opposite is true. Police corruption is systematic, entrenched and widespread, intertwined with shady businesses that require police protection to operate.
How close some of the relationships between policemen and local influential figures around the country are was evident in the Nakhon Pathom shooting.
Every time a police corruption scandal makes headlines, calls for reform arise. However, nothing substantial ever happens.
Coup makers always promise to combat corruption and reform the police. The most recent came from the 2014 coup leader and former prime minister Gen Prayut Chan-o-cha.
He ordered police to overhaul the promotion system, improve police welfare, and enhance investigations, law enforcement, transparency, and people's participation.
For police reform, numerous committees have been set up which make similar recommendations time after time.
After nearly a decade under Gen Prayut, corruption remains pervasive as ever, if not more. The Nakhon Pathom shooting best exemplifies the state of police corruption today.
The latest recommendations from the People's Network for Police Reform and 102 civic groups provide more specific proposals.
A study on Thailand's underground economy by economist Prof Pasuk Phongpaichit revealed its massive size and close ties to the police, endemic corruption, and money politics.
Highway police corruption is a small part of the underground economy from which cops benefit from protection money.
From 1993 to 1995, the underground economy in Thailand was estimated to be worth 297-457 billion baht per year, accounting for 8-13% of gross national product (GNP).
The figures now will have increased greatly. According to the study, if other illegal activities such as smuggled goods, logging, and human trafficking to third countries were included, the figures could reach 20% of GNP.
To protect their illegal empires, godfathers often enter politics and become major vote-buying donors.
Their political influence explains the lack of political will to combat corruption and reform the police, perpetuating the cycle of corruption and money politics that hurt democracy.
Interestingly, Prime Minister Srettha Thavisin did not mention police reform in his policy declaration early this week. This is deeply worrying.
Police reform is not only about cleaning up the police but also about ending the sinister relationship between the mafia, politics, and money politics.
It is imperative for the government to initiate police reform to give genuine social justice and transparency a chance.