The suspected killer of a policeman in western Moscow was detained in the early hours of Tuesday, the chief spokesman for the Russian capital's police told RIA Novosti.
"Last night at 02:00 in the Moscow Region village of Tuchkovo agents from the Moscow criminal investigation department... arrested the suspected murderer of police officer Denis Klimovich," Viktor Biryukov said, identifying the suspect as Yakub Kartakayev.
A law-enforcement source said Kartakayev had confessed to the crime.
Klimovich was shot dead early on Saturday when he and a colleague stopped a BMW car and asked to see the driver's identification. His colleague, Konstantin Bykov, was seriously injured in the incident.
"The detainee admitted that he was involved in robberies in Moscow and had gone out on Friday night out to commit a crime too, but was stopped by police and opened fire," the source told RIA Novosti.
Klimovich died at the scene, while Bykov was taken to a hospital and underwent surgery for wounds to the abdomen and shoulder.
Investigators found a passport belonging to a resident of the North Caucasus republic of Dagestan at the scene, and reports said that one of the three assailants may have been injured when police returned fire.
Biryukov added that Kartakayev had an injury, and that his father had helped to find him.
"The best agents in Moscow were put on the case to find the killers of the policeman," Biryukov said.
