A UN envoy confirmed Monday that a video allegedly depicting Sri Lanka troops executing Tamil Tigers was authentic, and that the action were \"definitive war crimes\". \"What is reflected in the extended video are crimes of the highest order -- definitive war crimes,\" said Christof Heyns, UN special rapporteur on extrajudicial, summary or arbitrary executions. \"I believe that the prima facie case of serious international crimes has been made by the video that I\'ve examined,\" he told the UN Human Rights Council. \"The inquiry should now be taken to a further level on an international as well as on domestic level.\" Heyns had examined a video provided by Britain\'s Channel Four, which had aired extracts on August 25, 2009. Following the broadcast of the extracts, Heyns\' predecessor Philip Alston had probed the authenticity of the footage shot during the final stages of the Sri Lankan army\'s battle against the Liberation Tigers of Tamil Eelam (LTTE) separatists. Alston concluded on January 7, 2010 that the extracts were genuine. However, his findings have been rejected by Sri Lankan authorities. On Monday, Heyns presented findings of his own investigation into a longer version of the video -- five minutes of footage, and drew the same damning conclusion as his predecessor. His investigation drew from findings by a forensic pathologist, two forensic video analysts, as well as a firearms expert.