MADRID, Spain — Spain’s National Court convicted the three main suspects in the Madrid commuter train bombings of mass murder yesterday and sentenced them to tens of thousands of years in prison for Europe’s worst Islamic terror attack.

But the verdict was a mixed bag for prosecutors, who saw four other key defendants convicted of lesser offenses and an accused ringleader acquitted altogether.

With much of the case resting on circumstantial evidence, the three judges may have been wary after a number of high-profile Spanish terror cases were overturned on appeal.

Spain’s prime minister said the verdict still upheld justice. But victims of the attack, which killed 191 people and wounded more than 1,800 when bombs exploded on four trains on March 11, 2004, expressed shock and sadness over the court’s decision.

“The verdict seems soft to us,” Pilar Manjon, who lost her 20-year-old son in the attack and has become a leader of a victims association, said. “I don’t like it that murderers are going free.”

Three lead suspects — Jamal Zougam and Othman Gnaoui of Morocco and Emilio Suarez Trashorras of Spain — were convicted of murder and attempted murder and received prison sentences ranging between 34,000 and 43,000 years. Under Spanish law, the most they will spend in jail is 40 years. Spain has no death penalty or life imprisonment.

Mr. Zougam was convicted of placing at least one bomb on a train and Mr. Gnaoui of being a right-hand man of the plot’s operational chief. Mr. Trashorras, who once worked as a miner, was found guilty of supplying the explosives used in the bombs. One of the biggest surprises was the acquittal of Rabei Osman, an Egyptian already convicted and jailed in Italy for the Madrid bombings.

Italian authorities said Mr. Osman bragged in tapped Arabic-language phone conversations that he was the brains behind the Madrid plot. But translations of the taped conversations by two sets of Spanish translators indicated his comments were more nuanced and did not amount to a confession.

The Spanish verdict came just two days after an Italian appeals court upheld Mr. Osman’s conviction there, but shaved two years off his prison term, sentencing him to eight years.

Mr. Osman watched the Spanish proceedings on a videoconference link from the Justice Palace in Milan. The Europa Press news agency reported that he broke down in tears and shouted: “I’ve been absolved! I’ve been absolved!”

Four other top suspects — Youssef Belhadj, Hassan el Haski, Abdulmajid Bouchar, and Rafa Zouhier — were acquitted of murder but convicted of other charges that included belonging to a terrorist organization. They received sentences of 10 to 18 years in prison. Fourteen other defendants were found guilty of lesser crimes and six others were acquitted.

Much of the evidence in the 57-session, five-month trial was circumstantial. Mr. Bouchar, for instance, was seen on one of the bombed trains shortly before the attack, but at trial no one could definitively identify him, and there were no fingerprints or other forensic evidence placing him at the scene.

A senior court official privy to the decision-making told the Associated Press after the verdict that the case against Mr. Osman was “flimsy” and that there was “no hard evidence” that Messrs. Belhadj or Haski were masterminds. The official agreed to discuss the verdict only if not quoted by name.

Circumstantial evidence is admissible in Spanish trials. But the judges may have avoided relying heavily upon it because of a number of high-profile terror cases that were overturned on appeal, including one involving a Spanish cell accused of involvement in the September 11, 2001, attacks on America, said Fernando Reinares, a former chief counterterrorism adviser at the Interior Ministry.

The trial was perhaps never going to produce the verdict some were looking for, since the seven men considered the true ringleaders of the 2004 attack were not in the dock. They blew themselves up at an apartment on the outskirts of Madrid as police moved in to arrest them three weeks after the bombings. Three other men are still fugitives, though two are suspected of having killed themselves in suicide attacks against American-led forces in Iraq.