1Activist blames Putin , Chechen leader for slaying .
2One of Russia 's most respected rights activists says Vladimir Putin and Chechnya 's strongman leader are responsible for the brazen murder of a human rights researcher .
3Rights advocate Natalya Estemirova was found dead Wednesday in Russia 's southern Ingushetia region after being kidnapped in adjacent Chechnya .
4It was the latest in a string of slayings of those who challenged or investigated the actions of authorities in Chechnya .
5Lyudmila Alexeyeva , head of the rights organization Moscow Helsinki Group , said Thursday that Russia 's powerful prime minister , Putin , is to blame for the slaying along with Chechen leader Ramzan Kadyrov .
6Alexeyeva said because Putin supports Kadyrov `` I blame both of them ... for involvement in the killing . ''
7Putin 's spokesman rejected the accusation .