Thai police opened an internal investigation on Monday after charges were dropped against a billionaire Red Bull heir in a fatal hit-and-run case as outrage boiled over a perceived culture of impunity for the rich.

Vorayuth “Boss” Yoovidhya, the grandson of the co-founder of energy drink giant Red Bull Beverage Co Ltd, was accused of killing a police officer when he crashed his Ferrari in Bangkok in 2012.

One of the heirs to the family’s multi-billion-dollar fortune, Vorayuth’s case received renewed public scrutiny after news on Friday that all charges against him had been dropped last month.

The public has latched onto “Boss” as an example of the kingdom’s ultra-rich apparently enjoying different standards, and have taken to social media to vent their anger.

Following a weekend of vitriol on Twitter which led to trending hashtags like #BoycottRedBull and #BossRedBull, a police spokesman announced a change of heart.

Spokesman Krissana Pattanacharoen said: “Police General Jakthip Chaijinda has set up an investigation team. The 15-day probe will find the facts and show transparency and justice to everyone to see whether the case followed police procedures.”

Police initially defended the decision, saying the attorney general’s office had sent them a letter in June informing them they were dropping the charges.

One of the charges of reckless driving causing death had several more years before the statute of limitations was set to expire.

But by Sunday afternoon, under pressure, the attorney general’s office announced it would set up a committee to investigate its own decision.

Red Bull’s maker TCP Group distanced itself from Vorayuth in a rare public statement on Sunday, saying he has never assumed any role in the company’s daily operations.