An 85-year-old doctor will appear in a Madrid court Tuesday, the first person to stand trial over an alleged practice that saw thousands of babies stolen under Spain’s military dictatorship during the mid-twentieth century.

Known as the lost children of the Franco-era, as many as 300,000 babies are estimated to have been abducted from their mothers under General Francisco Franco, who ruled Spain from 1939-75, and in the decades after.

The theft of newborns began in the 1930’s after the Spanish Civil War as an ideological practice, stripping left-wing parents or Franco-opponents of their children as a way of ridding Marxist influence from society. But in the 1950’s, the practice expanded to poor or illegitimate families who were seen as economically or morally deficient, Agence France-Presse reports.

New mothers were often told their babies had died and the hospital had taken care of the burials. These babies were allegedly sold for adoption and involved a wide network of doctors, nurses, nuns and priests, according to AFP. The system carried on after Franco’s death in 1975 until 1987, when a new law was implemented regulating adoption.

Dr. Eduardo Vela, who will appear in a Madrid court Tuesday, has been charged with falsifying official documents, illegal adoption, unlawful detention and certifying a non-existent birth, AFP reports. The former gynecologist is accused of having taken Ines Madrigal, now aged 49, from her biological mother at birth, and given to another woman who was falsely certified as her birth mother.

Read More: Stolen Babies: Confronting Spain’s Dark Past

According to DNA tests, Madrigal is not related to her late parents. Before her adopted mother died in 2016, Madrigal told a judge that she had been given by Vela as “a gift,” the BBC reports.

Campaigners say at least 2,000 other similar cases have been filed with Spanish prosecutors but until now, none have gone to trial, AFP reports.

The trial is scheduled to begin at 10 a.m. ET (8 a.m. GMT).

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