By Frances Harrison
BBC correspondent in Colombo
The International Red Cross (ICRC) has restarted investigations into the disappearance of 11,000 people during Sri Lanka's civil war.
Soldiers and civilians have disappeared
Both sides in the long-running conflict have requested the investigations.
The issue of the disappeared has been raised during peace talks and the ICRC asked to help set up an independent verification system for soldiers and civilians whose fate remains unknown.
But there are still formidable obstacles to finding out what really happened.
The ICRC says it has received 20,000 complaints of disappearances during the course of Sri Lanka's ethnic conflict.
Of those, 9,000 cases have been resolved - many of the missing people being traced to prisons and detention centres.
But 11,000 cases remain on their books and investigators have been working their way through these, checking for fresh information, now that there is no fighting and it is easier to move about.
Some mothers are able to find family members
So far, the ICRC has confirmed that more than 2,000 people remain unaccounted for, but by the time they finish this operation, the figure is likely to be far higher.
The question is whether this exercise will result in answers for the thousands of families who live in a state of limbo; unsure whether to mourn or keep on hoping.
The head of the Red Cross delegation to Sri Lanka, Marco Brudermann, told journalists it was not the ICRC that could provide the answers - it was up to the parties themselves.
If the Sri Lankan military or the Tamil Tiger rebel group is unwilling to admit responsibility for involuntary disappearances there is no way for the ICRC to force them to co-operate.
Even commissions of inquiry which have legal powers to call witnesses to testify have failed in the past to provide any redress to the families of the disappeared.
But the head of the ICRC delegation in Colombo, Marco Brudermann, said he thought it was a very positive sign that the government and Tigers were tackling the issue of the disappeared at this early stage in the peace process.
He said he was quite convinced both sides were aware of the implications and knew that courageous steps had to be taken.