Article published on the 2009-07-16 Latest update 2009-07-16 13:18 TU
Earlier this month, Memorial and Human Rights Watch issued a report accusing Chechen security forces of punishing families of alleged rebels by burning down their homes.
Memorial said that Estemirova had particularly angered local authorities when she accused security forces of carrying out an extra-judicial execution of an alleged rebel in public in front of his village on 7 July.
The group has explicitly blamed Chechen leader Ramzan Kadyrov for the killing. Kadyrov has brought a degree of stability to the region but is accused by activists of sanctioning a string of abuses.
Maria Shpikalova of Memorial in Moscow told RFI that Estemirova had been threatened by Kadyov. Shpikalova says the Chechen leader told Estemirova that he had "blood on his hands" and that he was "not ashamed of it."
"I was killing before and will be killing bad people," he said.
However, Kadyov voiced outrage over the murder and pledged to personally oversee the investigation.
Russian President Dmitry Medvedev condemned the killing just two hours after the murder was confirmed.
In July 2007 Estemirova was awarded the Anna Politkovskaya prize, named after the murdered Russian journalist, who was a friend and collaborator of Estemirova.