In Sri Lanka, Libya, Bahrain and elsewhere, human rights abuses are being recorded and the evidence is on the internet

The broadcast last week of Channel 4's Sri Lanka's Killing Fields documentary was a defining moment not just for the media, but for those who investigate war crimes. Chronicling the final bloody weeks in 2009 of the country's civil war which claimed the lives of at least 40,000 Tamil civilians, it captured in sometimes grainy, often terrifying footage, the horrors of a nation violently divided.