A flashy Thai cop nicknamed "Joe Ferrari" for his taste in fast cars was on Wednesday jailed for life for torturing a drugs suspect to death during a brutal interrogation.

A Bangkok court found Thitisan Utthanaphon guilty of murder by torture in a case that caused public outrage and shone a rare light on police brutality and corruption in the kingdom.

Leaked viral footage showed Thitisan and six other officers wrapping seven plastic bags around 24-year-old Jirapong Thanapat's head while questioning him and trying to extort $60,000, leading to his death.

The judge at Bangkok's Central Criminal Court for Corruption and Misconduct Cases sentenced the 41-year-old to death, but immediately commuted it to life imprisonment.

"I felt helpless during the ruling, and my wife was crying," Jakkrit Klandi, the victim's father, said outside the court.

"All seven officers should learn their lesson and pay for their crime," he said.

Thitisan Utthanaphon was found guilty of murder by torture
Thitisan Utthanaphon was found guilty of murder by torture THAI NEWS PIX via AFP / Krit Phromsakla Na SAKOLNAKORN

The court reduced Thitisan's sentence to life imprisonment because he had attempted to revive the suspect, and had paid for the funeral expenses for the family.

But Penh Thanapat, the Jirapong's mother, was not satisfied, telling reporters she never wanted to see Thitisan's face.

"I want (the death sentence). I want things to happen to him as it happened to my son," she said.

Thitisan looked healthy and was seen chuckling with guards inside the courtroom before the verdict, but closed his eyes as the sentence was read.

Five of the other six officers involved in the case were found guilty of murder and also received life sentences. A seventh got five years and four months, following his testimony.

Thitisan and the other officers have a month to appeal against the verdict, according to their lawyers.

Penh Thanapat, the victim's mother, told reporters she wanted the death penalty for Thitisan
Penh Thanapat, the victim's mother, told reporters she wanted the death penalty for Thitisan AFP / Lillian SUWANRUMPHA

The victim's parents said they were unhappy with the officers' offer of 600,000 baht ($17,000) compensation, with Jakkrit telling reporters he would consult lawyers.

They had initially asked the court for 1.6 million baht.

After the footage leaked in August last year, the officer -- a former district chief in the northern province of Nakhon Sawan -- surrendered himself to police, who raided his Bangkok mansion and found several luxury cars.

In a press conference after his surrender he said Jirapong's death was an accident.

Analysts and human rights observers cautioned that this verdict was not indicative of a wider shift in policing in Thailand.

"This relatively light sentence tells us that legal impunity for police is alive and well in Thailand," said Paul Chambers, of the Center of ASEAN Community Studies at Naresuan University in Thailand.

He said Thitisan and the other officers would likely have their sentences reduced on appeal.

Phil Robertson, Human Rights Watch's deputy Asia director, told AFP it was an "exceptional" case.

"For every case like this, there are dozens more where police torture is covered up, victims and whistleblowers face retaliation, and police impunity to commit abuses is alive and well," he said.

"This case may have put a temporary dent in the culture of police impunity in Thailand, but you can be sure that the overall system has not changed."