The case of Raymond A. Davis, a former United States Special Forces soldier who is being held in connection with the deaths of two Pakistanis, has stirred a diplomatic furor, sending the precarious relationship between the United States and Pakistan to a new low, both sides say. Mr. Davis, 36, was driving in dense traffic [when] two Pakistani men on a motorcycle tried to rob him. He shot and killed both and was arrested immediately afterward by police officers who say he was carrying a Glock handgun, a flashlight that attached to a headband and a pocket telescope. The mystery about what Mr. Davis was doing with this inventory of gadgets has touched directly on Pakistani resentments that members of the large American security presence here roam the country freely and are not answerable to the Pakistani authorities. The United States has warned Pakistan that if Mr. Davis is not released ... badly needed financial assistance could be cut. The public furor increased Sunday when the 18-year-old wife of one of the men Mr. Davis shot committed suicide, after saying she believed that the American would be unfairly freed. At the heart of the public outcry seems to be uncertainty over the nature of Mr. Davis's work, and questions about why his camera, according to police investigators, had pictures of buildings in Pakistani cities. One of the identification cards confiscated by the police after his arrest ... said he was a Defense Department contractor. Another ... said he was attached to the consulate in Peshawar, which contradicts an initial American Embassy statement on the day of the shooting that described Mr. Davis as a staff member of the consulate in Lahore.