US Senator Brad Sherman on Sunday asked the Pakistani authorities to ensure freedom of expression. In a video statement released after a telephonic conversation with PTI chairman and former prime minister Iman Khan, the US senator, who is a senior member of the Foreign Affairs Committee said PTI worker Zil-e-Shah was ‘tortured’ to death and his body was thrown on the road. The gruesome murder should be investigated and the elements involved in it should be held accountable, the statement said.