Birds twittering in the trees are among the few signs of life in Carter Camp, an abandoned former workers' housing compound now overgrown with untamed grass and where hundreds of bodies are buried in an unmarked mass grave.

Twenty years ago this week, one of the worst atrocities in Liberia's war — a conflict that was marked by its sheer brutality and high civilian casualties — occurred in Carter Camp when some 600 people were slaughtered on the night of June 5-6, 1993.

The neglect shown the victims mirrors the lack of action in bringing the perpetrators to justice. A United Nations-commissioned inquiry found the army of the late president Samuel Doe responsible, but other accounts have since challenged the report. No one was ever put on trial even though Liberia's post-conflict truth commission recommended prosecution for perpetrators of crimes in the war generally.

Nyenati Allison, who was then a reporter for The Associated Press, visited the area soon after the carnage and described a horrible scene: "Strewn through the camp were babies with crushed skulls, mothers hacked by machetes, elderly people butchered like livestock."

The victims were hastily buried. A profusion of bushes now renders the mass grave, dug between two aging trees on the outskirts of the old camp, all but inaccessible.

"The government needs to build a memorial here so that at least generations unborn will know what happened here," said Yelesah Mark, a 48-year-old survivor of that hellish night as he struggled to control his emotions.

Carter Camp existed originally as home for low-income rubber tappers of the Firestone tire company, situated 48 kilometers (30 miles) southeast of Monrovia near the world's largest rubber plantation which began operations in 1926. When fighting between rival rebel forces and regional peacekeepers displaced locals, they sought refuge in Carter Camp, swelling its population to over 3,000. By the time of the massacre, those in the camp of mud huts were a combination of company employees and people displaced by fighting.

The camp was immediately abandoned after the massacre and visitors have to be told there once was a camp here. Grass has taken over everywhere. Apart from a Nigerian-originated church which operates here, the few visible living things are birds building nests in trees that once provided shades for camp residents.

Mark was among the displaced people who nearly lost their lives in the Carter Camp Massacre, one of the worst atrocities in Liberia's 14-year civil war that ended in 2003. When gunmen dressed in military uniform entered the sprawling camp, said Mark, "we saw two tactical jeeps in which they came taking positions at the two ends of the camp, but we did not know their intent at first."

The slaughter soon began, with the attackers using firearms and machetes. Over 200 of those who were butchered were children.

"My brother-in-law Bainda and my friend Sackie were among the batch of displaced people slaughtered behind a poultry house down there," he said. "The killings were all over the camp; as people cried for help, all you could hear were 'ba-ba-ba, ba-ba-ba'" Mark said, imitating the sound of automatic weapons fire.

"Whenever I ... tell the story to people, it brings back that sad memory; it looks like we are digging out old wounds," he said. "But again, the story has to be told."

Mark said those who drove into the camp and carried out the massacre were former soldiers belonging to the army loyal to Doe. The then president was killed in 1990, but the army he led continued to remain active, fighting other rival forces.

Flan J. Nowon was a relief worker supervising food distribution in Carter Camp 20 years ago. He and his team worked there hours before the massacre, handing out food to "desperate people." They decided to take a break and return to their homes outside the camp, planning to return and resume the food distribution the next morning.

"It was just about two hours later that we started hearing heavy gunfire in the camp," Nowon said, standing with AP reporters near the overgrown mass grave. "I believed for sure there was something terrible happening in the camp when I saw a woman who had been shot in the buttock coming out of the camp naked, bleeding and crying and carrying a child."

"I ran back inside and told my wife 'Carter Camp is on fire,'" Nowon recalled.

The lack of accountability for massacres such as this one has bred suspicion that persists two decades later that some of those who orchestrated the violence are in positions of power.

Former Liberian President Charles Taylor, who was a leader of a rebel group in 1993 and whose fighters many people like Nowon suspect had a hand in the attack, was found guilty in April 2012 in an international war crimes court in the Netherlands of 11 counts of war crimes and crimes against humanity and received a 50-year prison sentence.

But that was for aiding and abetting rebels in neighboring Sierra Leone, not for atrocities in his own country.

"Liberia became a place where killing was a way of life," said Nowon. "And those who killed people deliberately in Liberia have been left to roam the streets."