A week of regional violence climaxed Monday in Ingushetia when a suicide bomber blew a hole in a heavily fortified police headquarters, killing at least 20.
Colleagues of Ms. Estemirova say her murder Wednesday is part of a pattern that shows cost of a Kremlin pact with Chechnyan President Ramzan Kadyrov.
Natalia Estemirova, who has long documented abuses by government-backed militias, is the fourth prominent critic of Kremlin policies to be killed in three years.
Yunus-Bek Yevkurov, the Kremlin-backed president of Ingushetia, is the fourth government official in the North Caucasus targeted this month.
The country is under the harsh, one-man rule of Ramzan Kadyrov, who wears a track suit, keeps a pet tiger, and urges men to take second wives.
Russia's military presence in Georgia has unnerved refugees who fled here from Chechnya in the 1990s.
Veteran Norwegian journalist Åsne Seierstad writes about mending the broken heart of Chechnya.