The United States says it hopes Russia will bring to justice the attackers who abducted and murdered Russian human-rights activist Natalya Estemirova. 

State Department spokesman Ian Kelly in Washington said the United States was deeply saddened by news that Estemirova was shot to death Wednesday.

The U.S. statement praised her "uncompromising ... willingness" to reveal the truth about human-rights abuses, especially in Chechnya, "regardless of where that might lead."

Estemirova was kidnapped in Chechnya.  Authorities found her body hours later in Ingushetia, with gunshot wounds to the head and chest.

In Moscow, a spokeswoman said Russian President Dmitri Medvedev expressed "indignation" and ordered a top-level investigation of the murder.

Chechen President Ramzan Kadyrov said he was outraged by the attack, and he promised to find Estemirova's killers.  However, the Russian human-rights group Memorial, for whom she worked, said it holds the Chechen official responsible for the woman's murder.

Swedish Foreign Minister Carl Bildt, whose country currently holds the European Union presidency, said the EU condemns what it called a "brutal act."

In the aftermath of Estemirova's killing, Human Rights Watch said there appears to be an open season (hunting season) on those who try to bring attention to what the organization says are appalling human-rights abuses in Chechnya.

Members of Memorial say four men shoved Estemirova into a car as she left her home Wednesday in the Chechen capital, Grozny, and that witnesses heard her yell that she was being kidnapped.

Estemirova had collected evidence of kidnappings, torture and killings in Chechnya since the start of the second separatist war there in 1999. Chechen authorities have been highly critical of her work.

She worked closely in Chechnya with Russian journalist Anna Politkovskaya, another Kremlin critic who was murdered in Moscow in 2006.

In 2007, Estemirova was awarded the first annual Anna Politkovskaya Award, in honor of her colleague and friend. The prize was created by the group, Reach All Women In War, with the support of female laureates of the Nobel Peace Prize.