I also read about a theory that at least one of them (Oleg Neliubin I think) was killed on Sergei Butorin's orders, so he couldn't talk. Some informant said Butorin simply made a call to one of the many illegal phones in prison.
They were pretty much on the end trying to cut ties with Orekhovskaya and were up to try and take over Moscow on their own. That could also actually be a reason to get them killed.
Kurganskaya is the brigade that I know as most fucked up till the core. They didn't pay their own men money, the leaders just kept it for themselves. Others were given just money to buy food and to pay for their apartment. They made one guy to kill his best friend, as he hadn't killed anyone. That's why the group fell apart right from the start.
