Ceremonies were held Sunday in the Scottish town of Lockerbie to mark the 20th anniversary of the bombing of Pan Am Flight 103 in which 270 people were killed. In a report coinciding with the anniversary, a British newspaper claimed that fresh evidence has cast doubt on the conviction of the Libyan man serving a life sentence for the bombing. New forensic analysis on a fragment of the timing device alleged to have triggered the bomb that brought down the plane is said to have found no trace of explosive residue, the Mail on Sunday reported. Lawyers acting for Abdelbasset Al Megrahi, the 56-year-old Libyan jailed for life for the bombing in 2001, will present the evidence at a forthcoming appeal. His legal team says the new information supports claims the timer was planted by investigators in a politically motivated attempt to incriminate Libyan leader Muammar Gaddafi. Sources close to his defence team say the tests should have revealed significant traces of explosive residue. The fragment was said to have been found by police in a singed shirt 25 miles from the Scottish town where the New York-bound Boeing 747 came down. A source close to the investigation was quoted as saying: "The only piece of forensic evidence in the chain that pointed to Libyan guilt has never been near the seat of an explosion." Megrahi, a former Libyan intelligence agent, is suffering from prostate cancer. Doctors said in October that he had less than a year to live. Several leading experts closely connected to the case told The Jerusalem Post last year they believed that Megrahi's conviction for the bombing - the deadliest terrorist attack ever mounted in the UK - would be overturned on appeal. Megrahi is the only man ever convicted for the bombing, in which 259 passengers and crew, and 11 people on the ground, lost their lives. A second Libyan defendant, Lamin Khalifah Fhimah, was acquitted. Libya, which was held responsible for the attack, has paid compensation to victims' families. Megrahi, who has always denied involvement, lost an appeal against his conviction in 2002, and was only given leave to mount a second appeal in June 2007. A Scottish legal review commission found six potential grounds for a miscarriage of justice, including flaws in the process by which he was identified and, reportedly, the non-disclosure of a classified report on the timer purportedly used in the bomb. The commission referred the case back to the Scottish courts. The overturning of Megrahi's conviction could revive the bombing investigators' original theory, widely believed by many of those close to the case, that Lockerbie was not a Libyan plot at all, but was, rather, carried out by Ahmed Jibril's Popular Front for the Liberation of Palestine-General Command, on behalf of Iran. Among the leading figures who publicly voiced this assertion was then trade minister Ariel Sharon, who told a press conference in Madrid seven weeks after the bombing, "Israel believes it was Ahmed Jibril." The spokesman for the Lockerbie victims' families, the UN's observer on the case and the Scottish law professor who formulated the legal framework under which Megrahi was tried all said they were convinced the conviction will be overturned. Families' spokesman Dr. Jim Swire, whose daughter Flora was killed in the bombing, said he was certain that the new evidence would see Megrahi released, but that he feared it would be "convenient" for the appeals court to free the Libyan on "some semi-technical" count - "something along the lines of the prosecution having failed to give the defense access to all the evidence" - without the full truth ever coming out. Swire said he feared this full truth included "the deliberate fabrication of evidence" such as the timer fragment, in order to frame Megrahi and render Libya as the "perfect scapegoat" for Lockerbie. Hans Koechler, appointed as an "international observer" to the trial by the UN Security Council on the nomination of then secretary-general Kofi Annan, told the Post: "They'll cancel the judgement. The appeal court will decide that a miscarriage of justice has occurred, because of the unreliability of Tony Gauci's evidence." And Robert Black, the emeritus professor of law at the University of Edinburgh who formulated the complex legal mechanism that facilitated the original trial before Scottish judges in the Netherlands, said the same thing. "Megrahi will go free. He should never have been convicted. The evidence does not show him to have had anything to do with [the Lockerbie bombing]." More than 150 people attended a wreath-laying ceremony Sunday at Lockerbie's Dryfesdale Cemetery, which has a memorial stone for those who died in the attack. Two churches in the area also held services to coincide with the moment the plane came down, just after 1900 GMT on December 21, 1988. Services were also held at Heathrow Airport in London and in the United States.