NEW YORK : A prominent international human rights watchdog body Wednesday called on Pakistani authorities to conduct a "prompt and impartial" investigation into the May 7 killing of human rights activist and lawyer Rashid Rehman, and bring those responsible to justice. “Pakistan’s vaguely worded blasphemy law has led to discrimination, persecution, and murder. It should be reformed or repealed immediately,” said Brad Adams, Asia director at Human Rights Watch said in a statement.