Pakistani prosecutors have decided to hold Davis for at least eight more days as an investigation into the deaths of two Pakistani civilians continues.
The U.S. State Department says its efforts to secure Davis' release are "extreme."
"We have raised this issue at the highest levels of the Pakistani government, including President [Asif Ali] Zardari," State Department spokesperson P.J. Crowley told 9NEWS late Thursday afternoon.
Crowley said that Secretary of State Hillary Clinton personally called President Zardari on Wednesday to talk about the impasse. The State Department says the conversation was "encouraging."
"We are obviously very concerned. The longer he is in jail and given that there are public tensions, we don't want to see anything happen to him, so that's why, from the Secretary of State, to our ambassador, to others, we continue to press this with the Pakistani government and we want to see it resolved as quickly as possible," Crowley told 9Wants to Know.
Davis currently rents a home in Highlands Ranch with his wife and his business is registered in Colorado. The U.S. State Department says he was working as a member of the U.S. Embassy's "technical and administrative staff" at the time of the Jan. 27 shootings and "cannot be lawfully arrested or detained in accordance with the [Vienna Convention on Diplomatic Relations of 1961]."
"He's a U.S. diplomat," Crowley said. "He has full criminal immunity."
Davis is accused of shooting and killing two Pakistani civilians one week ago in Lahore. The State Department says he "acted in self-defense when confronted by two armed men on motorcycles."
The reaction in parts of Pakistan has been dramatically less forgiving. Protestors have massed in the hundreds and occasionally in the thousands over the last week to demand that the Pakistani government not release Davis.
Davis was back in a courtroom in Pakistan again on Thursday. Reuters reports Davis was brought in an armored car and that journalists were barred from the proceedings.
"The police officials told the court that investigations have not yet been completed. The judge extended the remand for eight more days," Abdul Samad, a deputy prosecutor, told Reuters following the hearing.
"They do understand they're under international obligations and they're just trying to work this out with local authorities. I think we are confident that in the next few days this case will be resolved," Crowley said.
The story has generated intense coverage in the Pakistani press. One newspaper dubbed Davis "the American Rambo."
University of Denver Professor Ved Nanda is an expert in international law. He believes the Pakistani government is simply stalling and knows what it has to do in the end.
"If his name has been submitted to the government of Pakistan as a diplomat working in the political arena, he has got complete immunity and Pakistan cannot take action against him," Nanda said.
So why has it not happened yet?
"For their own constituency they have to show that they are not going to bow to American pressure. They don't want to be seen as timid," Nanda said.
DU International Studies Professor Shaul Gabbay says the entire story puts the Pakistani government in a vulnerable position.
"The central government is very weak," he pointed out. "At the grassroots level, the sentiment against the United States is growing."
"There is no question that [the government] could try to assert its independence [from American interest] by using this case and not adhering to the demands of the US, and therefore we are walking a very sensitive line here," Gabbay said.
(KUSA-TV © 2011 Multimedia Holdings Corporation)