BUENOS AIRES — Victoria Montenegro recalls a childhood filled with chilling dinnertime discussions. Lt. Col. Hernán Tetzlaff, the head of the family, would recount military operations he had taken part in where “subversives” had been tortured or killed. The discussions often ended with his “slamming his gun on the table,” she said.

It took an incessant search by a human rights group, a DNA match and almost a decade of overcoming denial for Ms. Montenegro, 35, to realize that Colonel Tetzlaff was, in fact, not her father — nor the hero he portrayed himself to be.

Instead, he was the man responsible for murdering her real parents and illegally taking her as his own child, she said.

He confessed to her what he had done in 2000, Ms. Montenegro said. But it was not until she testified at a trial here last spring that she finally came to grips with her past, shedding once and for all the name that Colonel Tetzlaff and his wife had given her — María Sol — after falsifying her birth records.