In May 2009, Sri Lanka's decades long civil war with the Tamil Tigers, the Liberation Tigers of Tamil Eelam came to a bloody close after government forces launched a massive offensive.

What exactly happened during the last days of the battle is still the subject of fierce debate, but it is clear that as the rebel perimeter shrank, around a third of a million civilians were trapped between the two armies and tens of thousands were killed.   

The government says the LTTE were using civilians as human shields, Tamil exiles say the deaths were the result of indiscriminate shelling by the Sri Lankan army. The LTTE was crushed in the offensive, most of its leaders killed and thousands were captured and imprisoned but the Sri Lankan government has so far refused to agree to an independent, international war crimes investigation.     

Now a UN panel has found that the allegations against both sides are credible saying they may have committed serious violations of humanitarian law.  

As Juliana Ruhfus and Dom Rotheroe have been finding out, unless and until the truth is established, a final reconciliation in Sri Lanka may prove impossible.   

Some of the images in their film are deeply disturbing.

This episode of People & Power can be seen from Wednesday, April 20, at the following times GMT: Wednesday: 2230; Thursday: 0930; Friday: 0330; Saturday: 1630; Sunday: 2230; Monday: 0930.