Massera, known as “Commander Zero,” died after a massive brain hemorrhage, the source said.
He had been in hospital after a 2003 hemorrhage, in a near-vegetative state, after which justice authorities deemed him incompetent for trial.
The former admiral was one of the military chiefs behind the 1976 coup that toppled Isabel Peron. It set up in power a junta led by army general Jorge Videla and air force brigadier general Orlando Agosti.
Massera was the head of the navy and in charge of the feared Naval Mechanics’ School (ESMA) which was one of the dictatorship’s main torture centres. About 5,000 political prisoners went in and only about 100 lived to tell.
Next to the ESMA was a grim maternity ward in which babies were snatched from their abducted mothers, their identities changed and their fates determined by military rulers.
The former admiral, who was accused of crimes against humanity during the 1976-1983 dictatorship, was declared mentally incompetent by his doctors back in 2005, after which all legal proceedings against him were dropped.
But his work at the ESMA will send him to “the gallery of Argentine historic figures as the biggest mass murderer in the history of the republic to date,” historian and journalist Osvaldo Bayer wrote in the prologue to his book “Massera, Behind the Genocide” (2000).
A blue ribbon investigative panel found that 11,000 people were killed during the dictatorship, most for being real or perceived sympathizers of the left. Some human rights groups put the number as high as 30,000.
Massera was sentenced to life in jail in 1985 in a landmark civil trial of the junta members and other military staff. He was pardoned in 1990 by then-president Carlos Menem.
But in the mid-1990s trials against the military government leaders were allowed to reopen, including one about the robbing and identity changing of some 500 babies born in captivity. In 2007, Menem’s pardon was annulled.