The arduous task of searching for and naming the dead

Less than 10 kilometers (six miles) from Damascus's busy city centre, in the northwestern suburb of Adra, there is a barren expanse of land enclosed by concrete walls.

As you drive, on the left side, a team of rescuers from the humanitarian organization White Helmets is visible searching for mass graves.

Over the past few days, videos have been posted online about mass graves in which Bashar al-Assad's regime buried those who were tortured to death in Syria's notorious prisons.

In Adra, the White Helmets found a small hole filled with large white plastic bags filled with the remains of bodies.

The message simply says: “Seven bodies, eighth grave, unidentified.”

The team was removing the remains, skulls and bones it found. DNA samples were collected. The remains were placed in black body bags for documentation and further analysis.

Ismail Abdullah, one of the rescuers, says that they carry a heavy burden on their shoulders.

“Thousands of people are missing,” he says. “It will take time – a lot of it – to get to the truth about what happened to them.”

He added, “Today, after receiving a call about the possibility of a mass grave here, we found the remains of seven civilians on the ground.”

He adds that all necessary measures have been taken “so that in the future we can identify the people who were killed.” This team is among the few people who have been trained to document and collect forensic evidence.

It is believed that more than 100,000 people have disappeared in Syria since 2011.

Last week, the rebel group Hay'at Tahrir al-Sham – which ousted Assad after more than 50 years of rule by his family – opened prisons and detention centers across Syria.

The rights group concluded that more than 80,000 missing persons had died. Another 60,000 people are believed to have been tortured to death, according to the UK-based Syrian Observatory for Human Rights.

Local residents are reporting more and more mass grave sites across Syria, as is the case of the Syrian Emergency Task Force (SETF), a US-based NGO.

Human Rights Watch says such graves must be protected and investigated.

At another site in the town of Qatifah, northwest of Damascus, the Special Task Force believes there is a mass grave that could contain the bodies of at least 100,000 people killed by the Assad government.

One local resident, who witnessed the burial of bodies over the years of the Syrian civil war, says they were packed in refrigerated containers brought in by security forces.

He told the BBC that the ground would be filled with corpses, and then the site would be leveled with bulldozers.

The religious leader of Katifa, Abdul Qadir Al-Sheikha, witnessed one of these mass burials.

He added that the secret police asked him to come and bury him. He was trying to perform religious rituals for the dead and pray for them.

He told me that in this 30 square meter space, at least 100 people were buried. He adds that after that he was not called again by the police.

“They called them terrorists who did not deserve to be buried,” Sheikha says. “They did not want anyone to witness what they were doing.”

Secret police prevented people from passing near mass grave sites or even looking out their windows as they carried out burials, another witness who was forced to participate told me.

The witness said that many of these mass graves are located on the outskirts of Damascus.

In another location in Al-Husseiniyah, on the road leading to Damascus Airport, satellite images show differences in the views of the areas where mass graves were discovered.

As the Assad regime collapsed in the face of the rebels' rapid advance, thousands of Syrian families rushed to prisons and detention centers to search for their missing loved ones.

They need closure and to honor their dead with a proper burial.

In one detention center, hundreds of identity cards belonging to Syrians held by Assad's security forces were scattered on the floor.

One woman was still searching for her missing brother, who disappeared in 2014. A father was searching for his son, who was arrested in 2013. And no one was ready to give up the search.

But locating and protecting mass graves and identifying the bodies they contain are tasks that only a few Syrians can currently undertake – and international experts are urgently needed to assist in this process.