The ageing former head of Argentina’s air force has been sentenced to 25 years in prison for the abduction and disappearance of a married couple of young activists during this country’s bloody 1976-83 dictatorship.

Former brigadier Omar Graffigna, 90, was sentenced on Thursday afternoon for the disappearance of Patricia Roisinblit and José Manuel Pérez Rojo, who were abducted in 1978 by the air force’s Buenos Aires Regional Intelligence (Riba) and never seen again.

At the time of her abduction, Roisinblit, a 25-year-old medical student, was eight months pregnant. She was kept alive by her captors for several weeks, then murdered after she gave birth. Her newborn baby boy was handed over to air force intelligence operative Francisco Gómez and his wife Teodora Jofre to raise as their own.

Roisinblit’s son, Guillermo Pérez Roisinblit, only found out his true identity at the age of 21 and was a plaintiff in the trial. Gómez, the man who he grew up believing was his father, was sentenced to 12 years for his part in the affair.

“Justice helps heal the wound,” Pérez Roisinblit told the Guardian, “but this will not bring my parents back to life, or help me find their remains and it does not compensate all the memories of them I never had because they were murdered when I was born.”

The 38-year-old senate employee and law student expressed frustration that Gómez has refused to reveal where his real parents were buried.

“I need to know that to be able to get on with my life and I am sure he has that information,” he said.

Pérez Roisinblit was also disappointed by Gómez’s relatively short sentence. “Considering the damage he did to me and to my family, 12 years is definitely not enough,” he said.

Also sentenced to 25 years for the couple’s disappearance was the former head of the Riba intelligence unit, Luis Trillo.

“I waited for 38 years to reach this moment,” Guillermo’s grandmother, 97-year-old Rosa de Roisinblit said in court. “The fight goes on. We’re not done here ... but, still, I never thought I’d live to see this moment.”

Some 30,000 mostly young people were murdered by Argentina’s military regime, according to human rights groups. It also believed that about 500 infants were born under similar circumstances to Pérez Roisinblit, of whom 120 have been reunited with their biological relatives so far.