It was not clear how many of them were killed by the (Lankan) army or whether the LTTE had moved the people to the war zones which led to the death of some of them. We may not have the full expertise to identify the exact factors that led to those casualties. So international participation is welcome for determining such causes. But the right to make the final judgment who was responsible for the deaths and on the nature of punishment should rest with the judicial system of Sri Lanka. The judicial system in Sri Lanka was in shambles earlier, but now it is returning to normal. The sovereignty of each country must be respected in such issues.
Wickremesinghe on investigating war crimes in Sri Lanka, quoted on Times of India, "Sri Lanka willing for international probe on war crimes says Lankan PM Ranil Wickremesinghe", February 12, 2016.