The BBC's Daniel Sandford in Washington said "broadly" families in the UK were concerned about the conviction, whereas US relatives were convinced of his guilt.
American Susan Cohen, whose 20-year-old daughter Theodora also died, said: "Any letting out of Megrahi would be a disgrace. It makes me sick, and if there is a compassionate release then I think that is vile."
But Pamela Dix, from UK Families Flight 103, said there had been a "lack of justice" for the victims, which included her brother Peter.
She told BBC Two's Newsnight she was "baffled" by much of the evidence in the trial that led to Megrahi's conviction in 2001.
'Just a tool'
And Martin Cadman, who lost his son in the bombing, said he believed Mergrahi was an innocent man who had acted with others.
He said: "As far as I know the Scottish authorities and no-one else has done anything to try and find who these others were that were supposed to be implicated, so the whole thing is really very unsatisfactory".