Raymond Davis, identified by Washington as a "technical administrative staff" official at the U.S. Consulate in Islamabad, is being held in the Jan. 27 killing of two Pakistanis.
Davis said the shootings were in self-defense as the Pakistanis had threatened to rob him. He faces additional charges of forgery for allegedly using a false name to apply for a visa.
U.S. State Department spokesman P.J. Crowley went on the defensive during his regular press briefing, denying allegations that Washington's relationship with Islamabad, a key ally on terrorism issues, was on shaky ground.
"The reports that we have suspended all contacts with the Pakistani government are not true," he said. "We continue to have high-level contacts in Pakistan and (in Washington) to be able to express to them the importance that we attach to resolving this issue and this case."
Crowley brushed off repeated suggestions that Davis was anything but a U.S. diplomat assigned to Pakistan.
"He is a U.S. diplomat. He was assigned to the embassy in Islamabad," he said. "He has immunity. And we again call for his release."