The four detainees are accused of stabbing the Kyrgyz man to death and stealing his mobile phone and 500 rubles ($20) on January 12.
"All four are accused that on January 12, in the town of Pushkin, after drinking alcohol they beat a Kyrgyz national, robbed him of 500 rubles and his mobile phone, after which they stabbed him in the neck and back causing the victim's death. They then dragged the body into nearby bushes, where they undressed him in an attempt to conceal their crime," the source said.
The Kyrgyz embassy in Moscow has sent the Russian Foreign Ministry, the Interior Ministry and the Prosecutor General's Office an official note expressing its deep concern over a spate of recent attacks on Kyrgyz nationals and foreigners generally in Russia.
The embassy said that at least four Kyrgyz nationals had been murdered in Russia over the past month.