You overestimate Putin's role in it and its importance. Ideology is at least a book. Z is just a symbol of the war, but not the ideology. Symbolism.
I admit cases of tortures, accidental and criminal death of civilians (like robbery, extorting money) not only from russian soldiers. But I deny its mass , organized character and especially its genocidal nature.
Besides, it is the war, a sign of torture could be a wound.
Imagine a simple case: soldiers captured an enemy soldier, surely he will be tied. Then a shell explodes and kill them all. One of corpses will have tied hands, wounds. If slightly blur vision, it can be called a victim of a torture.
Finally, if they found evidences, let them continue with the investigation and find the suspected.