Hours after the families of the two victims pardoned Davis under a blood money deal allowed by Islamic laws, US Ambassador Cameron Munter said in a statement: "I am grateful for their generosity. I wish to express, once again, my regret for the incident and my sorrow at the suffering it caused."
Munter confirmed that the Department of Justice had opened an investigation into the incident in which Davis shot and killed the two men in Lahore on January 27. The offer of such a probe was conveyed to Pakistan's top leadership by US Senate Foreign Relations Committee Chairman John Kerry during a visit to Islamabad last month.
Referring to the release of Davis, Munter further said, "I wish to express my respect for Pakistan and its people, and my thanks for their commitment to building our relationship, to everyone's benefit."
He reaffirmed the importance that US attaches to its relationship with Pakistan and the commitment of the American people to work with their Pakistani counterparts to "move ahead in ways that will benefit us all."
"This was a very important and necessary step for both of our countries to be able to maintain our relationship and remain focused on progress on bedrock national interests, and I'm deeply grateful for the Pakistani government's decision," Kerry said.
Now, both the countries can focus on the war against terrorism, he added.
Kerry, who visited Pakistan last month, said the US deeply regretted the loss of life that led to this difficulty in US-Pak relationship and the demonstrations on Pakistan's streets.
"But neither country could afford for this tragedy to derail our vital relationship. We look forward to working with Pakistan to strengthen our relationship and confront our common challenges," Kerry said.
Davis, a 36-year-old former Special Forces soldier, was arrested after he shot and killed two armed men he claimed were trying to rob him.
A third Pakistani man died when he was hit by a US consulate vehicle rushing to help Davis. Police rejected Davis' claim of acting in self-defence and booked him for murder.
He was freed by a court on Wednesday after the US paid Rs 6 crore to each of the families of the three dead men. The total diyat or compensation amounted to $ 2.3 million. Blood money is paid to the next of kin of a murder victim as a fine.
Pakistan-US relations plunged to a new low after Islamabad rejected repeated demands by Washington for Davis to be freed on grounds of diplomatic immunity.Pakistan's leaders, fearful of a public backlash due to growing anti-American sentiment, insisted that the matter should be settled by the courts.