Alias
"Tigre", "Santiago" y "Anibal"
Castellano

As Chief of the Intelligence Task Force Navy unit GT-332 based at the ESMA, he was ESMA's torturer in chief. He is responsible for about 5000 disappearances, tortures and murders, including the practice of throwing disappeared people alive into the Atlantic ocean from Navy planes. Among his victims are the Tarnopolisky family, the torture of numerous disappeared, and the disappearance of the families that met at the Santa Cruz Church. As the boss of Alfredo Astiz, Acosta is also responsible for giving the orders to kill the Swedish teenage girl Dagmar Hagelin, the French nuns of the Church of Santa Cruz, Leonie Duquet and Alice Domon, and the founder of the Mothers of Plaza de Mayo, Azucena Villaflor de Vicenti.

Acosta was clearly a psychopath. One minute he could be kissing a wanted prisoner through the man's hood, overjoyed at seeing him on the torture table of the ESMA, the next minute twisting the dial on the electric shock machine higher and higher, his face contorted with concentration. [Children of Cain, p.93]

Acosta's credibility evaporated as he began his testimony before a civilian court in December 1986; "I have no knowledge that there were prisoners in the Mechanics School", he said. In another time he added: "There were no detentions as such. It was like someone goes to a police commission and they're asked, 'Is this what you did?' If he said he did nothing ... he could leave."

Acosta had been indicted for Genocide in Spain, and is reported to work for members of the Menem government in Argentina, as well as for organized crime.

In 1998, it was found that Acosta had a Swiss bank account, presumably where he kept the proceeds from the thefts of the properties of the disappeared. In March, retired policeman Roberto Oscar González accussed Acosta of having been responsible of the operation to kill journalist Rodolfo Walsh in 1977.