Washington (CNN) -- Sen. Robert Menendez, D-New Jersey, announced Tuesday that the Senate Foreign Relations Committee has delayed a hearing scheduled for Thursday on the release of Abdelbaset Ali Mohmed al Megrahi, the Libyan man convicted in the 1988 bombing of Pam Am Flight 103.
Menendez said the hearing had been postponed because several key individuals asked to testify, including oil giant BP's CEO Tony Hayward, have declined to appear.
Menendez, who was set to chair the hearing, is part of a group of senators who have repeatedly voiced suspicions that Scottish authorities released al Megrahi as part of a deal allowing BP to drill off the Libyan coast BP, a British corporation, is already dealing with a public relations nightmare as the company responsible for the Gulf of Mexico oil disaster.
"The abundance of incredible coincidences" surrounding al Megrahi's release demands transparency, Menendez said Monday. "A cloud of suspicion" will hang over the issue until all of the relevant questions have been answered.
Senators need to know whether "blood was given for money," said Sen. Kirsten Gillibrand, D-New York. "We need to know that justice was served in this case."
The bombing of Pam Am Flight 103 resulted in the death of 270 people. Most of the bombing victims were Americans. The flight was headed from Frankfurt, West Germany, to New York via London, England, when it exploded in the air.
Al Megrahi was convicted in the case and sentenced to life in prison. The Scottish government released him on compassionate grounds in August after doctors said he had terminal prostate cancer and just three months to live. Al Megrahi is still alive, however, and news reports in recent days have questioned whether he was as sick as depicted.
Under the Scotland Act 1998, Scotland has its own government that is responsible for most of the day-to-day issues there, including the justice system.
Aside from the Hayward, the list of officials asked to testify included Scottish Justice Secretary Kenny MacAskill, who made the decision to release al Megrahi; Andrew Fraser, the physician who gave the prognosis that led to al Megrahi's release; and former British Justice Secretary Jack Straw. They all declined the committee's request.
In an effort to make clear that the Obama White House had opposed the release al Megrahi, the State Department on Monday released the text of an August 12 letter from Richard LeBaron, the No. 2 official at the U.S. Embassy in Britain, to Scottish First Minister Alex Salmond.
The letter stated that the U.S. government "maintains its view that in light of the scope of Megrahi's crime, its heinous nature, and its continued and devastating impact on the victims and their families, it would be most appropriate for Megrahi to remain imprisoned for the entirety of his sentence."
State Department spokesman P.J. Crowley said the administration was trying to "avoid the worst possible outcome: a hero's welcome for Megrahi in Libya. ... Unfortunately, the Scottish government did not heed those views."
At a joint news conference last week, Cameron and U.S. President Barack Obama blasted the decision to release al Megrahi.
BP has said it expressed concern to the British government in late 2007 about the slow progress of a prisoner transfer agreement that Britain and Libya were negotiating, saying it could have had a "negative impact" on British commercial interests.
But the company has denied involvement in any talks with either the British or Scottish governments specifically about al Megrahi's release.