Four of Spain's Civil Guard police officers were convicted today of torturing members of the Basque separatist group ETA after they were arrested for bombing Madrid's airport in 2006.

Tried in October, the officers were found guilty of beating and threatening to kill Mattin Sarasola and Igor Portu after they were taken into custody in 2008. The court said Sarasola had a gun pointed at his head, and Portu was dunked several times in a river.

Today's ruling came on the fourth anniversary of the attack at Madrid Terminal 4, which destroyed a five-story parking garage, killing two Ecuadorean immigrants and wounding 41 people.

ETA, which claimed responsibility for the bombing, has been seeking an independent Basque homeland in northern Spain and southwestern France for more than four decades. The group has killed more than 825 people and is considered a terrorist organization by the EU and the U.S.

The court sentenced one Civil Guard officer to 4 1/2 years in jail and the other three to terms between 2 and 2 1/2 years. The court found 11 other officers involved in the arrest operation innocent.

Sarasola, Portu and a third ETA member were convicted and sentenced earlier this year for their roles in the airport attack.

The car-bombing marked the end of a so-called permanent cease-fire that ETA had called in March 2006. The organization returned to violence with the airport bombing after peace talks with Prime Minister Jose Luis Rodriguez Zapatero's government went nowhere.

Spanish and French police have since arrested dozens of suspected ETA members in both countries. ETA has not committed a deadly attack since July 2009, when it killed two policemen on the island of Mallorca.