A former Canadian judge, Louise Arbour, is taking up the job of United Nations High Commissioner for Human Rights from Thursday.
Ms Arbour was a chief war crimes prosecutor for the UN
Ms Arbour, who used to sit on Canada's Supreme Court, is a former chief war crimes prosecutor for the UN.
She served on tribunals investigating the genocide in Rwanda and human rights abuses in the former Yugoslavia.
Ms Arbour replaces Sergio Vieira de Mello, who was killed in the bombing of the UN headquarters in Baghdad last August.
Vieira de Mello's deputy, Bertrand Ramcharan, had been acting as High Commissioner at the UNHCR's headquarters in Geneva since then.
During her three years as chief UN war crimes prosecutor, Ms Arbour acquired a reputation for being tough and uncompromising.
She also succeeded in increasing the number of suspects indicted for war crimes from seven to 34.
A criminal law specialist and veteran judge, Ms Arbour received her law degree from the University of Montreal in 1970.