Will Nemtsov's assassination affect Ukraine peace?

The assassination of a Russian opposition leader comes at a "very bad time" because it comes just an armistice is taking affect between Russia and Ukraine, California Sen. Dianne Feinstein, the top Democrat on the Senate Intelligence Committee, said on "Face the Nation" Sunday.

Boris Nemtsov, who was a leader of Russian opposition and a vocal critic of Russian President Vladimir Putin, was shot and killed early Saturday in Moscow. Feinstein said the intelligence community does not yet know much about the death.

"It's very difficult to get certain kind of intelligence with respect to Russia. But I think it speaks on its face as to what it is, someone very much opposed to the" Kremlin, she said. She described Nemtsov as "a distinguished dissident" who was widely respected and was "prepared to take on Russia with respect to the Ukraine and what Russia has really been doing there."

She said she believes that there is a connection to Putin, although only an investigation will show whether Putin authorized the assassination, knew about it, or if it was connected to him by way of friends or the military.

Following Feinstein's appearance, her spokesman, Tom Mentzer, said, "Sen. Feinstein was not asked if there was a connection between President Putin and the murder, she was asked if that is an important question to answer--and she agreed. The senator has no information regarding any involvement by President Putin, nor was she speculating on any connection. She does believe a thorough investigation is in order."

Host John Dickerson asked, "Is the key question about his assassination whether there's a connection to Vladimir Putin?" Feinstein replied, "Oh, I think so. I think there is. Whether Putin authorized it, whether he didn't, whether he knew about it, whether it was his friends or some of his military doing this, we'll wait and see with the investigation."

Feinstein also suggested Nemtsov's death could complicate efforts for diplomacy between Russia and Ukraine, where Russian-backed rebels have battled the military for control in the eastern part of the nation. Both sides had just begun to observe a recent cease-fire agreement.

"The only solution there is to work out a solution between the governments. And so this certainly presents an obstacle. And I hope that Mr. Putin will step up. I hope he will see that some diplomacy can prevail, that he can work out a solution with the Ukrainian leadership," Feinstein said.