Phnom Penh, Cambodia - Rong Chhun was visiting family in rural Cambodia when he received a phone call telling him that his good friend and colleague Chea Vichea, a prominent union leader, had been shot dead by two men on a motorbike.

Vichea, the charismatic president of the Free Trade Union of Workers of the Kingdom of Cambodia (FTUWKC), had been on a regular visit to a roadside newspaper stall in the capital, Phnom Penh.

That was on January 22, 2004.

"After he was shot, authorities sent his body to the pagoda," Chhun said. "When his relatives and I arrived, they had already prepared the charcoal and everything to cremate him."

Vichea's friends and family refused to let authorities dispose of the body without a formal autopsy, leading to a five-hour standoff.

While they did eventually recover Vichea's body, 15 years later, the killing remains one of the most significant unsolved crimes in Cambodia.

"He was a dedicated, intelligent, courageous and tireless colleague of mine," opposition politician Sam Rainsy, who helped Chhun and Vichea found Cambodia's first free trade union in 1996, wrote in an email to Al Jazeera.

No will

Two men were arrested for the murder, but witness accounts cleared them both. When the first judge dismissed the case, he was replaced with a new one who found both men guilty and jailed them for 20 years.

In the end, they were acquitted after five years in prison as Vichea's family and human rights groups campaigned for their release.

"The authorities don't have the will to do a real investigation because the killer is somebody powerful in the government," Chhun alleged.

The investigation resumed following the men's acquittal.

Government spokesman Phay Siphan refused to discuss the case and hung up when asked about the government's alleged connection to Vichea's murder.

Heng Pov, a former Phnom Penh police commissioner, claimed he knew what had happened, telling a French news magazine that the national police chief had pressured him into framing the pair, after earlier boasting the murder would be solved within a week.

Pov is now in jail himself after being convicted of a range of crimes, including the assassination of a judge.

"[Prime Minister] Hun Sen feared Chea Vichea's capability to bring worker unions to support an insurrection against his controversial regime," Rainsy said.

Chhun said the government, led by Hun Sen since 1985, has long feared the union movement because of its size.

Organisations are forced to operate within a range of restrictions that risk hamstringing leaders in a web of legal complaints, but there is also the risk of violence.

'Clear and principled'

In 1997, Vichea was wounded in a grenade attack on a political rally led by Sam Rainsy that left 16 people dead.

On another occasion, he was badly beaten by soldiers.

"He only went to meet workers during his lunch break to distribute his business card and explain their rights under the labour law," Mann Senghak, the current vice president of FTUWKC, said. Soldiers arrived to disperse the gathering, but Vichea refused to leave.

"His character was clear and principled. He gained a lot of respect from people because of what type of person and leader he was," Senghak said.

It was in 2003 that Vichea first began getting death threats.

"After he received threatening phone messages, we went to the police station to file a complaint," Chhun said. "A while later, the police said they cannot do anything because that phone number belonged to somebody high-ranking. They advised that Chea Vichea should try to get somewhere safe."

The two friends debated whether Vichea should leave the country, but ultimately he decided to set an example by standing his ground.

Vichea's widow, Chea Kimny, said that in the days leading up to her husband's murder, police and soldiers were hanging out in front of their home.

Kimny was pregnant at the time and their young daughter liked to go with her father to the newspaper stand, but that morning Vichea went alone.

"I saw that blood covered the newspapers and I asked: 'Where is my husband?'," Kimny said.

When she later saw his body at the pagoda, she fainted.

Pattern of violence

Vichea's assassination was not an isolated incident.

Just four months later, two gunmen on a motorbike shot dead Vichea's replacement, Ros Sovannarith, while Hy Vuthy, who defected from a pro-government union to lead the FTUWKC, met the same fate in 2006.

These deaths today may feel like a distant memory, but the 2016 assassination of political analyst Kem Ley shows the risk of political violence remains - and justice as elusive.

Kingsley Abbott, senior legal adviser for the International Commission of Jurists, said there had been a "marked decline in respect for human rights and rule of law in recent years" in Cambodia.

He pointed to the Supreme Court's dissolution of the main opposition party in 2017 and the unsatisfactory investigation into Ley's murder as evidence that the courts were still a "political tool".

"Until judges are free to act independently and impartially free from any interference, this trend is likely to continue," he said.

Struggle continues

In the years since Vichea's death, the $7bn garment industry has become the country's biggest formal employer, and some efforts have been made to appease workers.

But with Vichea's killing, the unions lost one of their most effective leaders.

"Living conditions and working conditions haven't improved much," Chhun said. "If Chea Vichea were alive now, the union movement would be a lot stronger and more organised. The government would have to be more careful and maybe even couldn't dissolve the opposition so easily."

While successes have been few and far between, the struggle never ends for Chhun, Senghak and others - they see it as a form of social justice in continuing the work of those who've been killed.

Human life in Cambodia is even cheaper than a dog’s life in Finland. Chea Kimny

"As you know, a lot of union leaders were killed, beaten, sent to prison, or flee the country. It's dangerous for us but we have our dream to help workers have a better life so we keep fighting. If we leave then who will help?" Senghak asked.

Now living in Finland, Kimny says she would love to return to her homeland but doesn't feel safe. The memory of her husband's murder remains raw.

"I cry all the time when it gets close to the anniversary and think about what happened when he was killed," she said.

"I think human life in Cambodia is even cheaper than a dog's life in Finland."