An accused ringleader was acquitted altogether and four other top suspects came away with lesser convictions. In all, 21 of the 28 people on trial for alleged participation in the March 11, 2004 bombings were found guilty on at least some charges.
Seven defendants got off entirely including an Egyptian who prosecutors alleged bragged that he masterminded the attacks. The blasts killed 191 people and injured more than 1,800.
Four other top suspects Youssef Belhadj, Hassan el Haski, Abdulmajid Bouchar and Rafa Zouhier were acquitted of murder but convicted of lesser charges including belonging to a terrorist organization. They received sentences of between 10 and 18 years.
Much of the evidence against the men was circumstantial, but prosecutors had hoped it would add up to convictions. Bouchard, for instance, had been placed on one of the bombed trains shortly before the attack, but at trial nobody could definitively identify him.
While observers say circumstantial evidence is admissible in Spanish court, it is possible the judges were loath to rely 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 Sept. 11 attacks.
The three lead suspects convicted of murder and attempted murder each received sentences ranging from 34,000 to 43,000 years in prison, although under Spanish law the most time they can spend in jail is 40 years. Spain has no death penalty or life imprisonment.
The three are: Jamal Zougam, a Moroccan convicted of placing at least one bomb on one of the trains; Emilio Suarez Trashorras, a Spaniard who is a former miner found guilty of supplying the explosives used in the attacks; and Othman Gnaoui, a Moroccan accused of being a right-hand man of the plot's operational chief.
A senior court official, speaking on condition of anonymity, said the evidence against the acquitted Egyptian, Rabei Osman, was "very thin."
Osman, who is in jail in Italy, had allegedly boasted in a wiretapped phone conversation that the massacre was his idea. But his defense attorneys argued successfully that the tapes were mistranslated.
Judge Javier Gomez Bermudez read out the verdicts in a hushed courtroom, with heavy security, including bomb-sniffing dogs and police helicopters, outside.
In addition to Osman, six lesser suspects were acquitted on all charges. Fourteen other people were found guilty of lesser charges like belonging to a terrorist group, bringing the total number convicted to 21 of the 28 defendants.
Prime Minister Jose Luis Rodriguez Zapatero, who came to power after the attacks, welcomed the verdicts. "Justice was rendered today," he said.
The attacks have "left a deep imprint of pain on our collective memory, an imprint that stays with us as a homage to the victims," said Zapatero.
Most of the suspects are young Muslim men of North African origin who allegedly acted out of allegiance to al Qaeda to avenge the presence of Spanish troops in Iraq and Afghanistan, although Spanish investigators say they did so without a direct order or financing from Osama bin Laden's terror network.
Bermudez said the probe had turned up no evidence of involvement by the armed Basque separatist group ETA, dismissing the initial argument of the conservative pro-U.S. government in power at the time of the attacks. The theory is still embraced by many Spaniards.
The blasts targeting crowded, morning rush-hour commuter trains arguably toppled its government the first time an administration that backed the U.S.-led Iraq war was voted out of power.
That day of carnage, wailing sirens and cell phones going unanswered amid the wreckage of blackened, gutted trains is etched in Spain's collective memory and is now widely known as simply 11-M, much as the term 9/11 conjures up so much pain for Americans.
Seven suspected ringleaders of the attacks including the operational chief and an ideologue blew themselves up in a safe house outside Madrid three weeks after the massacre as special forces who tracked them via cell phone traffic moved in to arrest them.
The attacks had profound political repercussions and left Spaniards deeply and bitterly divided between supporters of conservatives in power at the time of the massacre and Socialists who accused the government of making Spain a target for al Qaeda by supporting the Iraq war and sending in 1,300 troops.
The government of then-Prime Minister Jose Maria Aznar initially blamed Basque separatists for the bombings, even as evidence of Islamic involvement emerged.
This led to charges of a cover-up to deflect attention away from the government's support for the war, and in elections three days after the bombings the conservatives lost to the opposition Socialists, who quickly brought the Spanish troops home.