A review of US government records found no information about BP attempting to influence the release of the Lockerbie bomber, a committee hearing in America has been told.
Members of the United States Senate Foreign Relations Committee are investigating the circumstances of the release including whether it was linked to an oil deal - a suggestion strongly denied by all parties involved.
On Wednesday, Nancy McEldowney, a principal deputy assistant secretary in the State Department, said the department had "not identified any materials, beyond publicly available statements and correspondence, concerning attempts by BP or other companies to influence matters" related to Abdelbaset Ali Mohmed al-Megrahi's release.
The Libyan is the only person to be convicted of the 1988 bombing of Pan Am Flight 103 over Scotland, in which 270 people died - most of them Americans.
Scottish Justice Secretary Kenny MacAskill released the prostate cancer sufferer on compassionate grounds 13 months ago after he was given three months to live, but he remains alive today.
The decision sparked fury in America and was condemned by President Barack Obama's administration.
The Foreign Relations committee was told that Ms McEldowney had noted that in 1998 the US and Britain wrote a letter to the secretary general of the United Nations, outlining an agreement for Megrahi and another suspect to be tried before a Scottish court established in the Netherlands. The letter stated: "If found guilty, the two accused will serve their sentence in the United Kingdom."
She said that back then, the US sought binding assurances that would happen, but the British countered that they could not legally bind the hands of future governments. "They nonetheless assured us of their political commitment that, if convicted, al-Megrahi would remain in Scotland until the completion of his sentence," Ms McEldowney said.
The committee hearing was postponed earlier this year after key witnesses including former justice secretary Jack Straw, Mr MacAskill and Scotland's First Minister Alex Salmond turned down requests to attend.
A Scottish Government spokesman said on Wednesday night: "With the US State Department saying that there is no evidence whatever that BP played a role in the release of al-Megrahi, the entire basis of the Senate committee hearing has fallen away - we have been telling them that in letter after letter, and in a meeting, for many months."