The murder of Nemtsov was planned and organized very professionally. The timing was done in such a way which makes it likely that the anti-Putin march was organized beforehand as its next and well timed action in a series. The place, on the bridge (a symbol over[coming] Moscow, the river, and right by the Kremlin) too had been clearly very carefully chosen.
Moreover, one also needs to assume that Nemtsov was very probably led to the place of his death by his Ukrainian "girlfriend" (read: hired female escort).
What the FSB was doing or apparently not doing when it failed or was told not to maintain surveillance of Nemtsov--for his own protection--and when it also failed to make up anything of the fact that his Ukrainian escort was also a lover of one of the Kiev Nazi battalions, remind one of the very kind of "provocations" and very professional "unprofessionalism" which planned and pulled off in order to change the communist regimes (from above) in Eastern Europe in 1989.
Moreover, while the Ukrainian escort of Nemtsov, who apparently walked Nemtsov to his death, was called the main and sole [??] witness of the murder, she was very suspiciously allowed to go (escape) very quickly, too quickly, back to Ukraine where Avakov himself quickly declared that she was not coming back for further investigation.
On top of that, she might or should have been also included among the possible suspects of the murder. But this did not seem to occur to anyone and, clearly, a decision was made very high up not to even demand that she stay in the country during the necessary investigation. I repeat--the fact that Nemtsov's Ukrainian escort with links to Kiev Nazis was so quickly released, without the clever investigators not even allowing for a possibility that she too might have been one of the suspects (for all practical purposes, she herself could have shot him), makes one not just wonders, but absolutely stunned.
Now, with the arrest, accusation and killing of Kadyrov's men serving in Chechnya's pro-Russian security forces, the investigators (or Moscow itself) are also "masterfully" (absolutely unprofessionally) challenging the honor and stability in Chechnya--on top of having the murder fuel, swell, and energize the liberal Maidan of regime change. The quickly cooked rewarding of Kadyrov does not make all these strange and connected lapses any better.