BISHKEK, Kyrgyzstan — A top U.S. envoy called Saturday for an independent investigation into the violence that has devastated southern Kyrgyzstan, as amateur video emerged of unarmed Uzbeks gathering to defend their town during the attacks. Prosecutors on Saturday charged Azimzhan Askarov, the head of a prominent human rights group who shot the video, with inciting ethnic hatred. Askarov had accused the military of complicity in the bloody rampages that sent hundreds of thousands of Uzbeks fleeing for their lives. The country's rights ombudsman Tursunbek Akun insisted the charges against Askarov were fabricated, and activists in Bishkek demonstrated before U.N. offices to demand his release. Valentina Gritsenko, head of the Justice rights organization, said she feared Askarov was being tortured. He was detained with his brother on Tuesday in his southern hometown of Bazar-Korgon, colleagues told The Associated Press.