The murder of Russian human rights activist Natalya Estemirova should be thoroughly and impartially investigated by Moscow, UN Secretary General Ban Ki-moon was quoted as saying on Thursday. Ban urged Russian authorities to bring the attackers to justice and send "a strong and unambiguous message that the targeting of human rights activists will not be tolerated", dpa reported. Ban expressed "solidarity with human rights defenders around the world who work courageously and selflessly each and every day in the defence of basic rights and freedoms." Estemirova was kidnapped from her house in Grozny, Chechnya, and murdered on Wednesday.