Utthanaphon's lifestyle may have continued had the CCTV footage not been leaked to Sittra Biabungkerd, a lawyer who put the video on Facebook. He told AFP he wanted to stop police "helping each other to get away" with murder.
Born into an ordinary family, Utthanaphon won spots at the prestigious Armed Forces Academies Preparatory School, and the Police Cadet Academy, before he married into wealth in 2009.
The couple were often seen at high society events and when the marriage fell apart a few years later, he remained a familiar face among Bangkok's elites, where he made headlines for his fondness for fast cars and dating a string of glamorous actresses and models.
In 2014, the Bangkok Post reported he made a very public proposal to actress Pichanak "May" Sakakorn, getting down on one knee at the Millennium Hilton in front of her A-list celebrity friends. The marriage did not go ahead and he is now linked to a famous TV host, whose father is a senior police officer.
Some of Utthanaphon's substantial wealth came from auctioning hundreds of imported luxury cars seized by Thai customs. Until recently, police officers were paid "finder fees" for confiscating smuggled cars.
Investigators were due to submit their findings to the National Anti-Corruption Commission on Friday before deciding whether to forward the case to the state prosecutor.
Officers involved in the suffocation of Jeerapong Thanapat in an alleged attempt to extort about $85,000 initially tried to resuscitate him before taking him to hospital and insisting he had collapsed from an amphetamine overdose. The video dispelled those claims.
Utthanaphon now stands accused of murder, abuse of power and other offences - all charges he denies. Prof Pavin Chachavalpongpun, a Thai academic in exile now teaching at Kyoto University, Japan, said the case exposes "deep-rooted" corruption that has become normalised.
Poor salaries and benefits were partly to blame, he said. "This opened the door for the police to use their power to make more money for themselves."
The well-connected officer was once at the heart of the opaque system of power networks that rule the Southeast Asian nation, but the public, who have faced decades of extortion at the hands of the police appear to be running short of patience.
Chachavalpongpun said cries for police reform had been a key demand of recent mass pro-democracy protests. "Overall, it is about transparency, accountability and responsibility. So that's why what happens inside the police fits in well with the public agenda of the protesters," he said.
The Government has tried this year to kickstart police reform by amending the National Police Act.
