Thinking about this more, it is strange to me Putin would want to kill Nemtsov. Contrary to how your media seems to be describing him as a big opposition leader, he really was not all that.
He was a guy who was supposed to be President after Yeltsin and got pushed aside in favor of Putin. That is why he became some kind of an “activist”, or “dissident”; not because he really wanted to help people or whatever. Just wanted power back.
I did say he was a patriot, and I believe he was that, at least, he certainly, in my conversation with him, seemed to genuinely believe what he was doing was for the good of Russia. He protested the conflict with Ukraine because Russian boys were and are dying there along with Ukrainians. I respect that.