The United States has again called for the release of US citizen, Raymond Davis, involved in the killing of Pakistani nationals in Lahore. State Department spokesman Philip Crowley said Davis is a member of the embassy's technical administrative staff and therefore entitled to full criminal immunity. Crowley said he cannot be lawfully arrested or detained in accordance with the Vienna Convention. The spokesman said Washington agreed with the US employee's version of events that he acted in self-defense, when confronted by two armed men on motorcycles.Earlier a Pakistani lawyer called for the American who shot dead two men last week to stand trial for murder despite US legal claims of diplomatic immunity. Local lawyer Saeed Zafar filed the petition under public interest laws, claiming that Davis must stand trial in Pakistan.