Spain's Supreme Court on Thursday upheld the acquittal of a top suspect in the 2004 bombings of commuter trains in Madrid, rejecting an appeal by prosecutors on the grounds he has already been convicted of the same crime in Italy, an official said. Rabei Osman, an Egyptian, was one of three alleged masterminds cleared of mass murder in the bombings at a trial in Madrid in October. The court ruled that because Osman had already been sentenced to eight years in prison in Italy, he could not be condemned again for the same crime, a court official told The Associated Press on condition of anonymity because of departmental rules. Spanish prosecutors had argued unsuccessfully that Osman was appealing his Italian sentence, leaving the door open for his trial here. In Spain, both prosecutors and defendants can appeal lower court decisions. Ten backpack bombs ripped through four packed trains carrying early-morning commuters on March 11, 2004, killing 191 people and injuring more than 1,800 in Europe's worst Islamic terror attack. Twenty-one people - including three masterminds - were convicted during the five-month trial that ended in October. Seven others, including Osman, were acquitted. The Supreme Court altered several other sentences in its ruling Thursday, slightly reducing the sentences of some of those convicted of lesser charges. It also reversed the acquittal of Antonio Toro, sentencing him to four years in prison for exchanging explosives used in the attack for drugs and money. Osman was arrested in Italy in June 2004 after allegedly saying in wiretapped conversations that the attacks were his idea. He repeatedly has denied it was his voice in the calls, and his Spanish defense lawyers also questioned the translation of the call used in the Italian court. The long trial was a painful reminder to Spaniards of one of the blackest days in the country's history. Jesus Ramirez, a survivor of the attacks who until recently was vice president of a victims' association, said he accepted the judges' decision, even if he did not agree with it. "Even though we may oppose it in our hearts, they have more information and have weighed the evidence and made a decision," he told the AP. A two-year Spanish investigation concluded that the killings had been carried out by homegrown radicals, inspired by al-Qaida's call to arms but with no direct link to Osama bin Laden's group.