A court sentenced a former navy spy known as “the Angel of Death” and 11 other former Argentine military and police officers to life in prison Wednesday for crimes against humanity committed during the 1976-83 military dictatorship.

Alfredo Astiz, a 59-year-old ex-navy captain, became notorious for his infiltration and betrayal of activists and was viewed by many Argentines as the symbol of the junta’s crimes. He was accused of participating in the kidnapping, torture and murder of two French nuns, a journalist and three founders of a human rights group.