Eight years into a war that has killed over half a million people, Syrians whose relatives have been kidnapped or detained are hoping to get more information about the fate of their family members.

Out of a total 143,176 detentions or kidnappings during the war, the so-called Islamic State (IS) was responsible for at least 8,143, according to the Syrian Network for Human Rights.

Human Rights Watch, an international NGO, is now working with a new coalition of families who have joined together to find missing relatives.

“There should be a mechanism to investigate the fate of those (who have) disappeared and give an answer to the families,” Nadim Houry, Human Rights Watch counterterrorism director, told Euronews' Good Morning Europe.

If their family members have been killed, “they have a right to know, and they have the right to give them a proper burial,” he added.

Human Rights Watch is now calling for a database to be formed to collate information on the missing and help under-resourced authorities as they go through mass graves in Syria.

In 2018, the NGO documented efforts in Raqqa to identify bodies in mass graves in former IS-controlled areas. The organisation determined that these efforts were diligent but “rudimentary”.

In an interview with Good Morning Europe, Houry said that many actors in the Syrian Civil War were “bureaucratic” and kept records of detainees.

Over 89% of those known to be detained or an estimated 127,916 individuals are missing at the hands of Syrian regime forces, according to the Syrian Network for Human Rights. The human rights organisation said as of March 2019, those individuals were still held in government detention centres.

“The Syrian government has maintained clear records of who’s in detention,” Houry said. “The problem is it’s not sharing those records with anyone.”

Families in north-eastern Syria have often been unable to find information from security forces, hospitals, or first responders. But Houry said even members of the IS kept meticulous records.

“The problem is it hasn’t been a priority so far of the Syrian Democratic Forces or of the International Coalition to really look into this issue,” he said.

Watch Good Morning Europe’s interview with Nadim Houry, Director of the Terrorism and Counterterrorism Programme at Human Rights Watch, in the above video player.