Prosecutors in a southern Russian region said Tuesday they were investigating a man who claimed he posted a video on the Internet showing the brutal execution of two men from Central Asia and the Caucasus. The three-minute video elicited outrage among Russian hate crime monitoring groups and was disavowed by some nationalist groups. It also stoked concerns about the marked rise in xenophobia, racism and hate crimes that have swept the country in recent years. The prosecutor's office in the Adygeya region said a man was under investigation on charges of inciting ethnic hatred. He was released from custody on condition he not leave town. A police official said the man was a student in his early 20s who turned himself in Tuesday in the Adygeya capital of Maikop and identified himself to authorities as a Russian nationalist. Police searched his home and seized his computer, the official said. The video, which appeared Sunday on several ultra-nationalist Web sites, shows two men kneeling in the woods in front of a Nazi flag with their arms and legs bound. Their mouths are wrapped in clear tape and they speak in barely audible voices: "We were arrested by Russian national socialists."