With reporting by NTV, Interfax, ITAR-TASS, and RIA Novosti

Police in Moscow have detained hundreds of youths who had gathered on October 15 to protest the killing of an ethnic Russian in a southern district of the Russian capital.The police action came hours after authorities arrested a migrant laborer suspected of the slaying.Police said they had detained a native of Azerbaijan, Orkhan Zeynalov, in connectionwith the killing last week of a 25-year-old Muscovite in the neighborhood of Biryulyovo.According to Russian media reports, Zeynalov resisted special forces when they tried to detain him in Kolomna, a small town outside Moscow.Zeynalov is accused of fatally stabbing Yegor Shcherbakov in front of his girlfriend while they were walking home on October 10.That death stoked ethnic tensions and brought Russian nationalists into the streets for a demonstration on October 13 that devolved into lawlessness hours later, as bands of young men broke shop windows and overturned cars.A total of 23 people, including eight police officers, were injured when some of those rioters stormed a vegetable warehouse in Moscow's Biryulyovo district, where Zeynalov reportedly worked.Speaking to RFE/RL's Azerbaijani Service within hours of his arrest, Zeynalov's father insisted his son was innocent and suggested he was the victim of a setup."This was planned from start to finish," Zahid Zeynalov said. "This is some kind of political case that was pre-planned. What can I say?"After news that police were seeking an Azerbaijani national in connection with the killing on October 15, a spokesman for Azerbaijan's Interior Ministry said authorities there were ready to help their Russian colleagues find Zeynalov, if such help were requested."This person has never been wanted in Azerbaijan and is not on a wanted-persons list now," spokesman Ehsan Zahidov said. "[Moscow police chief Anatoly Yakunin] claims that Russia addressed Azerbaijan asking for help. I must say that up to this date, the Russian law-enforcement agencies have not sent any request to the Interior Ministry of Azerbaijan. None at all. Of course, if they file a request, we will consider it."Aleksei Pronkin, a Moscow resident who rented out a room in his apartment to Zeynalov, alerted police late on October 14 after recognizing him on television.Pronkin told journalists that he had watched the news together with Zeynalov earlier that day and he had joked about Zeynalov's resemblance to the blurry picture of the suspect first released in the media.He said Zeynalov had then hurriedly packed his bags and left on an alleged business trip.Pronkin finally recognized him as the suspect after a second, more detailed, picture was published several hours later."I saw that it was him," he told reporters. "The blue jacket was also his. That was exactly his face there."Police detained some 1,200 migrants from Central Asia and the Caucasus at the vegetable warehouse in question on October 14.Amnesty International, on October 16, condemned the mass arrests, calling them "the latest example of disproportionate and discriminatory policing in Russia."