Secretary of State Hillary Rodham Clinton canceled a meeting last weekend with Pakistani Foreign Minister Shah Mehmood Qureshi at an international security conference in Munich to protest Allen's detention, according to officials from both countries who were not authorized to discuss the situation on the record.
The administration has twice summoned Pakistani Ambassador Husain Haqqani to the White House for formal complaints and demands that Pakistan recognize Davis's diplomatic immunity and release him immediately. The message was repeated in a meeting in Islamabad Monday between Pakistani President Asif Ali Zardari and U.S. Ambassador Cameron Munter.
Davis, 36, holds a diplomatic passport and is a member of the "technical and administrative staff" at the U.S. Embassy in Islamabad "entitled to full criminal immunity in accordance with the Vienna Convention," the State Department said Monday.
The administration and Congress, the statement said, "have repeatedly made clear at the highest levels that this matter must be resolved by the Pakistan government or it could impact other bilateral initiatives."
In Pakistan, the issue has become embroiled in widespread anti-Americanism and suspicions, fanned by the Pakistani media and used for political advantage, that U.S. spies and intelligence contractors are secretly operating in the country. It has also posed a challenge to Pakistan's weak civilian government as it struggles to wrest control of national security policy from the powerful military and fends off opposition political parties.
The most powerful opposition group, the Pakistan Muslim League headed by former prime minister Nawaz Sharif, rules Punjab province and its capital, Lahore, where Davis is being held and several hearings have taken place in the case.
Although the administration has been unequivocal in its insistence that Davis has diplomatic status, it has been less than clear on the nature of his job in Pakistan over the last two years. An early embassy statement said it was "security" related, while officials in Washington have said that he vetted questionable visa applicants. The CIA has declined to comment on the case.
On Thursday, the Lahore court extended Davis's detention for another eight days. The U.S. Embassy complained that it was given no notice of the hearing, that Davis had no attorney present, and that he was not provided with an interpreter.
"He was denied due process and a fair hearing," the statement said. "His continued detention is a gross violation of international law."
Although Zardari's Pakistan People's Party government has close relations with the administration, and depends on the billions of dollars in U.S. military and economic assistance, it fears being painted as a U.S. lackey.
A foreign ministry official said that the government itself is divided over the case. The ministry has determined that Davis is immune from prosecution based on his passport and diplomatic visa, and the fact that Pakistan "accepted" that when Davis first arrived in the fall of 2009, the official said.
Other parts of the government, he said, see some advantage in using the situation to prove the government's independence from Washington. But the Americans, he said, "have dropped hints they could go to any extent" to get Davis released.
Further complicating the situation, a Pakistani intelligence official said that the two men Davis killed were not, as he has said, armed robbers intent on stealing money, his telephone and perhaps his car, but intelligence agents assigned to tail him. This official said the two intended to frighten Davis because he crossed a "red line" that the official did not further define.
Both the military's Inter-Services Intelligence service and the Interior Ministry's Intelligence Bureau regularly use motorcycle tails to track the movement of U.S. officials, another Pakistani official said.
The Pakistani media has also suggested that Davis is being held hostage to a wrongful-death case brought in New York by family members of four Americans killed in the 2008 terrorist attack in Mumbai, India. U.S. and Indian officials have blamed the attack on the Pakistani organization Lashkar-i-Taiba, which has long-standing ties to ISI. Four senior ISI officials, including the organization's director, Lt. Gen. Ahmed Shuja Pasha, have been called as witnesses in the case.
According to his 2009 visa application, Davis was born in Wise, Va. He gave an address in Las Vegas, where he is listed in Nevada state registration records as the co-owner of a firm called Hyperion Protective Services.
On Sunday, the widow of one of the men killed by Davis committed suicide in the city of Faisalabad. According to a doctor at the hospital where she was admitted after ingesting rat poison, she said she did it because she feared Davis would be released without facing trial.
Brulliard reported from Islamabad. Special correspondent Shaiq Hussain in Islamabad contributed to this report.