They just killed for the fun of making movies, it seems.
I think that the situation over there is different. Mountain Chechens live in another world - divided in clans (hostile one to another with long lasting vendettas), close knit, with traditional robbery, confused by modernity, by recent Wahabi influences and by their Western admirers.
The Chechens who have more brains or desire for better life left for the Russian cities long time ago. In fact most of them did. Some are troublemakers (organized crime) but many are productive normal citizens.
This Polish anarchist group was engaging in Western phantasy of brave tribal freedom fighters and ugly Russophobic hatred. They were brainwashing confused Chechens with this "noble" vision. But when one clan was more into traditional kindapping (they need to make living in these poor mountains somehow) the dreamy delusion was crushed by the morbid reality.
I recommend the film Prisoner of the Mountains that "introduces a world that is likely to be unfamiliar to most Western viewers."
If the Western PC doogooders, Big Game players and Saudi sponsors stop to meddle, Russia might quiet down the situation by delevoping peaceful local Chechen leadership focused on economic and cultural development. It will take time, but it is only humane solution.