“You cannot close the book on the life of a loved one if you do not know the truth, or what the reasons were, why people went missing,” said Salvadoran diplomat Augustin Vasquez Gomez.
His country, where some 8,000 people are still missing after years of civil war, has become one of the latest nations to sign a treaty pledging to support the work of the International Commission on Missing Persons (ICMP).
In the Philippines, also a signatory to the treaty, there are still 2,000 missing after Typhoon Haiyan struck in November 2013.
And while finding and identifying the missing killed in conflicts or disasters is an age-old problem, no overall global figure has ever been determined.
The numbers are thought to be “staggering” – between 250,000 and a million in Iraq alone stretching back to the early days of the regime of former dictator Saddam Hussein, said Kathryne Bomberger, ICMP director general.
The organisation, which finances its painstaking research through voluntary donations, held a recent seminar on its work as it moves its headquarters from Sarajevo to The Hague.
Born out of the conflicts in former Yugoslavia and set up in 1996 by then US president Bill Clinton, the ICMP has used sophisticated DNA matching techniques to identify more than 70 per cent of the 40,000 who went missing in the Balkans wars.
Now it is shedding its ad-hoc status to become a recognised international organisation – the only one dedicated exclusively to accounting for the missing.
It hopes to open a new lab in the Dutch city in the coming months, to complement its first one in Sarajevo which already has the capacity to handle up to 10,000 DNA cases a year.
Demand is growing. And as the conflicts in Syria and Iraq feed a new wave of refugees, hundreds of whom have perished at sea lacking any kind of documents, a new challenge is emerging.
After five years of civil war and a huge exodus from the country, there are an estimated 60,000 missing Syrians.
“There’s nothing we can do in Syria for the moment, but we’re already losing time in terms of collecting data from survivors,” Ms Bomberger said.
She’s hoping to try to move into the refugee camps, build up trust with families there and start organising a valuable data base.
Every day Syrian families are contacting the organisation for help finding relatives, and the ICMP is already working with Italian authorities to try to identify the dead washing up on Italy’s shores.
In Iraq on Mount Sinjar, it has been working to identify mass graves from the Islamic State group’s persecution of the Yazidi people, protect the sites and catalogue the DNA of the dead.
And that’s without mentioning conflicts in Africa or Asia, where there are also many families waiting to claim their dead.
“Part of what we want to do and focus on is demographics, for once to try to get a handle on how many people are missing in the world,” said Ms Bomberger.
“Most countries don’t have accurate figures because of the highly political nature of these conflicts.”
Identifying the dead is also crucial, if those behind the world’s worst crimes are to be successfully held to account, said Kweku Vanderpuye, senior trial lawyer at the International Criminal Court.
“Often, the perpetrators of those crimes operate under the principle: no bodies, no crime,” he said.
For those left with no grave to mourn over, there is an overwhelming sense of loss, of farewells left unsaid, a raw grief which does not fade as the decades pass.
“Our truth is hidden in mass graves,” said Munira Subasic, president of the Mothers of Srebrenica, who lost 22 members of her extended family in the 1995 genocide in the Bosnian enclave.
She told the seminar how one Bosnian Muslim mother died in Srebrenica a few days ago, still mourning her son whose body has never been found.
“Her last words were that if she had been so lucky to find just one little piece of bone she would have wrapped it in silk and kept it for herself. And it would have made her the happiest person in the world,” said Ms Subasic.