We want justice for Natasha

Today marks a week from the abduction and murder of Chechen human rights activist Natalia Estemirova. A week after her murder, nobody has been charged for this crime and Natalia's organisation, Memorial, the only human rights group left working in Chechnya, has announced that it is closing down.

We are all supporters of the human rights organisation RAW in WAR (Reach All Women in WAR), and in October 2007, on the eve of the anniversary of Anna Politkovskaya's murder, we presented to Natalia Estemirova the first annual Anna Politkovskaya award, to recognise women who are defending human rights in zones of war and conflict, often at great personal risk.

We are shocked and outraged by the killing of Natalia Estemirova in Chechnya last Wednesday. We presented the Anna Politkovskaya award to her for her courage in seeking and telling the truth about the torture, disappearances and murders of civilians in the war in Chechnya.

Natasha (as she was known among friends and colleagues) was a gentle, loving woman and a brave truth-teller who was not afraid to speak out about torture, rape and disappearances in Chechnya. She paid for it with her life. Like Anna did. Because there is nothing more dangerous than telling the truth in today's Russia. And Natasha was a truth-seeker with every fibre of her being. She just couldn't remain silent; she couldn't play it safe. She was a fierce spirit, a whistleblower, a caring and loyal friend, a deeply loving woman, who stood up for humanity.

Like Anna, she was killed because she told the truth about the "dirty war" in Chechnya. She was a condemned woman – giving voice to condemned people: the people of Chechnya. Natasha was a unique woman whose courage earned her death threats and abuse from the authorities at home, and the love and admiration of human rights supporters at home and around the world. She lived a life of courage and truth-telling in the face of grave danger, as Anna did.

We call on the Russian government to bring to justice both those who killed Natasha Estemirova and those who ordered her murder, and to end the killings of journalists and human rights defenders in the Russian Federation. We call on the Russian government to bring to justice the killers of Anna Politkovskaya, for whose murder, three years on, justice has not been done.

We also call on the world's leaders to demand justice for Natasha and safety for her colleagues from the human rights group, Memorial, in Chechnya, and to pledge to do everything in their power to protect the journalists and human rights defenders who work in areas of war and conflict, and who speak out on behalf of the victims, as Natasha and Anna did.

On 6 October 2008, on the eve of the anniversary of Anna's murder, Natasha presented the Anna Politkovskaya award to the courageous young parliamentarian from Afghanistan, Malalai Joya, with the words: "Malalai, be brave." We owe it to the memory of Natasha and Anna to protect the very few who still speak out on behalf of those to whom nobody wants to listen.

Mairead Maguire, Jody Williams, Shirin Ebadi, Rigoberta Menchu Tum, Elena Bonner, Tatiana Yankelevich, Anna Yankelevich, Vaclav Havel, Desmond Tutu, Jon Snow, John Pilger, Andre Glucksmann, Gloria Steinem, Sergey Kovalyov, Alexei Simonov, Vladimir Bukovsky, Malalai Joya, Gillian Slovo, Mariana Katzarova, Adam Michnik, Tom Stoppard, Bernard-Henri Levy, Natasha Kandic, Elisabeth Rehn, Zbigniew Brzezinski, Mariane Pearl, Asma Jahangir, Carl Gershman, Hina Jilani, Susan Sarandon, Jane Birkin, Sophie Shihab, Eva Hoffman, Naomi Klein, Sister Helen Prejean, Ariel Dorfman, Vanessa Redgrave, Eve Ensler, Michael Cunningham, John Sweeney, Jonathan Schell, Noam Chomsky, Marina Litvinenko, Heidi Bradner, Lyudmila Alekseeva, Desmond O'Malley, Anne Nivat, Marek Edelman, Annabel Markova , Frank Judd, Nicolas Rea, Anthony Giddens, Nazir Ahmed, Shirley Williams, Molly Meacher, Vivien Stern, Helena Kennedy QC, Professor Yakin Erturk, Elena Kudimova, Sister Marya Grathwohl, Meglena Kuneva, Stina Scott, Esther Chavez, Anna Stavitskaya, John D Panitza, Dubravka Ugresic, Katrina vanden Heuvel, Victor Navasky, Aidan White, Caroline McCormick, Holly Near, Elizabeth Frank, Elizabeth Kostova, Zoe Sallis-Huston, Denise LeBoeuf, Julian Popov, Oleg Panfilov, Stefan Tafrov, Tsvetana Maneva, Mihail Simeonov, Susan Allee, Edward Friedman, Arlene Lederman, Bill Bowring, Amanda Sebestyen, Andrey Nekrasov, Irena Grudzinska Gross, James Lecesne, Cal Skaggs, Laura Flanders, Elena Cook, Martin Dewhirst, Zoya Grannes, Elena Jandova, Marta Coigney, Jenny Diski, Monica Ali, Isa Blyden, Nayereh Tohidi, Claire Bertschinger, Georgi Borissov, Vanora Bennett

* This article was amended on Wednesday 22 July 2009 to remove one name that should not have been included among the signatories.