BUENOS AIRES, Argentina - Former dictator Jorge Videla was sentenced to life in prison Wednesday for the torture and murder of 31 prisoners in 1976.

The ruling thrilled victims' relatives who packed the courtroom, applauding and shouting "Murderers!" at Videla and other defendants when the verdicts were read.

Videla, who led the military coup that installed Argentina's 1976-83 dictatorship, is considered the architect of a dirty war that eliminated thousands of people in a crackdown on armed leftist guerrillas and their supporters.

The judges found Videla "criminally responsible" for the torture and deaths of the prisoners, who were pulled from civilian jail cells and officially "shot while trying to escape" as the military consolidated its power in the months after the coup.

Videla told the court that Argentine society demanded the crackdown to prevent a Marxist revolution and complained that "terrorists" now run the country.

Videla must serve his sentence in a civilian prison, the judges decided, ruling out the privileges he enjoyed after he was first convicted of crimes against humanity in 1985, as Argentina was struggling to return to democracy.

Videla served just five years of a life sentence in a military prison before former President Carlos Menem granted him and other junta leaders amnesty.

After a concerted campaign to reform a judicial system packed with dictatorship-era judges, the Supreme Court overturned those amnesties in 2007. Current President Cristina Fernandez has encouraged a wave of new trials of former military and police figures involved in the clandestine torture centers where thousands of the regime's opponents disappeared.

This was the first of dozens of trials due for Videla, now 85. This time, he was among two dozen defendants - most of them former military and police officials - charged with torture, murder, and cover-ups in the deaths of the 31 political prisoners in provincial Cordoba.

On Wednesday, most of the others also were sentenced to life in prison, although some received lesser terms, and seven minor defendants whose cases were joined to Videla's were found not guilty.