It is against the law in Russia to even speak about the war with Ukraine. Even being overheard in a restaurant conversation is enough for authorities to haul you in.
Speaking or writing about Russian causalities is also now unlawful and carries about a 5 year prison sentence. Mothers of Soldiers groups had previously used postings on VK (similar to facebook) for information as to where their sons were serving, and who was dead, injured, or had gone missing. That too is now against Russian law. In fact, simply posting an commendation or award for military action is now illegal.
However there is a way to find out if your son has been killed in Ukraine: Cargo200.
Cargo200 is a term used when dead Russian soldiers are transported. The website is
http://gruz200.net and so far there are almost 245 pages listing the names, info, and photos of dead Russian boys.
I understand that some of our Russian friends will insist that these are mere volunteers, rather than Russian regulars. Fact: when a Russian unit is assigned to enter Eastern Ukraine, every member of that unit is forced to sign a separation agreement. It means that the entire unit has "resigned" from the Russian Army (something conscripts can't really do in real life), and this allows the Kremlin to say that only volunteer Russians have entered Ukraine of their own free will. However, you can imagine what happens if a solder refuses to "volunteer" for such a mission. Naturally, those who come back alive are instantly considered to have never "separated" in the first place.