When the media does not report the obvious details about a criminal, leaving them vague and unsaid, the idea is probably to prevent people from generalising that all Chechnyans are murderers and thus reduce prejudice. I wonder if that is only true some of the time, and may backfiring. According to the Spectator, people are already reading the news differently, filling in the blanks and breaking the code on their own. The grim joke about reading Pravda was that you could sense the news in WWII: the Red Army was winning glorious battles closer and closer to Moscow every day.
In American politician crime stories, the party of the councilwoman or state senator is often omitted when they are a Democrat, but mentioned when a Republican (or mentioned in paragraph twelve instead of two). That is amply documented, though I have never seen any numbers on what the conservative pres does. Do they do the same mention/not mention, paragraph difference, or print the story/don't print it? I don't know. The uneven mentioning has over time likely contributed to false estimates in the general public. They know it is Donald Trump's supporters who are violent, not the protestors. They just know it, and believe they are deciding for themselves and sizing up the landscape objectively.
Yet something else happens as well. After getting burned enough times, conservatives now read so suspiciously that in the absence of information they likely draw the opposite conclusion. They assume they are being steered and bamboozled. I think this latter type of prejudice is stronger, and harder to get over. Though their opponents are still fewer than those they can still fool, the general media may have sown the wind and begun to reap the whirlwind. Over at Maggie's today, Sam L mentioned two sources which used to have reputations for evenhandedness, though for one this was long ago. He no longer trusts either, and has learned this at a hard school. I doubt he is rare.