A former naval officer dubbed the "angel of death" by survivors of the Argentine military's 1976-1983 dirty war against leftists is among 16 people sentenced here to prison terms ranging from 18 years to life for crimes against humanity.

Capt. Alfredo Astiz was the most prominent of the 18 defendants in the "mega-case" for abductions, killings and torture carried out by teams operating from the Navy Mechanics School in Buenos Aires, which functioned as the junta's largest secret prison.

Astiz, whose outspoken public defense of the military regime and fair-haired good looks have made him into a kind of emblem for the dirty war, and 11 other men were sentenced to life behind bars.

Four other defendants received double-digit jail terms, while two were acquitted.

Hundreds gathered outside the courthouse in Buenos Aires for the reading of the verdict, which they followed via closed-circuit television on giant screens installed for the occasion.

Many in the crowd were relatives of the roughly 5,000 prisoners who passed through the mechanics school, known by the Spanish acronym ESMA, during the dictatorship.

Nearly 200 witnesses testified during the 22-month-long trial, including dozens of ESMA survivors who faced their erstwhile tormentors in court.

The 18 accused faced 85 counts, including ones related to the killings of human rights activists Esther Ballestrino de Careaga, Azucena Villaflor and Maria Ponce and French nuns Alice Domon and Leonie Duquet.

All five of the women were abducted in December 1977 by agents under Astiz's command and died after being hurled into the Atlantic Ocean from aircraft.

The trial also dealt with the events of March 25, 1977, when intellectual and one-time militant Rodolfo Walsh was killed in a shootout with government commandos who ambushed him on a street in Buenos Aires.

A journalist and mystery writer who belonged to the Montoneros, an armed leftist faction within the Peronist Party, Walsh was slain one day after publishing his bitter "Open Letter" to the military junta on the first anniversary of the armed forces' seizing power.

"This is a historic day, it's the most worthy struggle in the recent history of the Argentines," his daughter, Patricia Walsh, said Wednesday after the verdict.

The junta leaders and those who carried out their orders were long shielded from prosecution thanks to amnesties approved by the Argentine Congress in the 1980s.

But lawmakers repealed those laws in 2003, opening the door for judges and prosecutors to re-open investigations of the crimes of the dictatorship, which killed some 13,000 people, according to official figures.

Human rights groups say the true death toll is closer to 30,000.

A declassified U.S. government document mentions a 1978 report from Chilean intelligence citing an official figure from the Argentine junta of nearly 23,000 dead in the first 2 1/2 years of military rule.