The murder of Boris Nemtsov in the immediate proximity of the Kremlin seems to be an important milestone in Russia’s descent into darkness. As Deputy Prime Minister in the late 1990s and as an opposition politician during the era of Vladimir Putin, Mr. Nemtsov was a voice for a more liberal, open, and democratic Russia.

Notwithstanding a certain degree of restraint in his criticism of the Russian government, his work as one of the central figures of Russian opposition reflected great personal courage. In spite of a history of frequent arrests, in the past year, he positioned himself as an important domestic critic of Russia’s war against Ukraine.

He was not a stranger to free market ideas or to the work of the Cato Institute, which has been trying to support the transition of Soviet Russia to markets since its landmark 1990 Moscow conference, Transition to Freedom: The New Soviet Challenge. One decade later, Mr. Nemtsov spoke at a Cato conference on the privatization of pension systems around the world.

The circumstances of Mr. Nemtsov’s death are extremely disconcerting, especially in the light of the track record of Mr. Putin’s regime. Mr. Nemtsov was killed two days before the planned demonstration against Mr. Putin’s war against Ukraine. He feared for his life as he was preparing to publish new evidence on the presence of Russian troops in Eastern Ukraine. And the ‘investigation’ of his murder started on Friday night, with the police ransacking his apartment and confiscating his documents and hard drives.

Mr. Putin’s facetious promise that he will “personally oversee the investigation” strongly suggests we will never learn the names of Mr. Nemtsov’s murderers. But it is safe to say that a country in which opposition politicians of Mr. Nemtsov’s stature have to fear for their lives is a on a very dismal path.