Dr. Vela will be the first person to stand trial for what victims' groups claim was a secret practise that saw up to 300,000 babies stolen.
The scandal covers the regime of fascist dictator General Francisco Franco, who ruled Spain from 1939 until his death in 1975 but some groups claim the practise went on into the 1980s.
Dr. Vela, a former obstetrician at San Ramon Hospital in Madrid, will go on trial on Tuesday, June 26, accused of stealing a newborn baby from her mother and giving her to another woman, a sample charge which is believed to have been the tip of the iceberg.
The "stolen babies" scandal only came to light about 10 years ago.
Biological Mothers Were Often Politically Suspect
The biological mothers were sometimes teenage girls or women who got pregnant out of wedlock but they were often simply women with suspect, left-wing, political motives.
They were taken from them and given to childless families who were loyal to Franco's Falangist movement.
In 2010 Ines Madrigal, 49, read an article about the affair which mentioned the hospital where she was born as being a focal point for child trafficking in the 1960s and 70s.
"I thought… my God, don't tell me that this is my case," Madrigal, a railway worker who now lives in the Murcia region, told the AFP news agency.
[Tweet: "The robbery and the sale of babies did not end with Francoism: I had a girlfriend who was born in 1980, which was delivered by a nun to her parents before payment of 6 million pesetas."]
Ms. Madrigal, who was born at San Ramon Hospital in 1969, had been told she was adopted by her mother when she was 18 but it was only when she saw the article in 2010 that she can to connect the dots.
Birth Certificate Was Falsified
She began her own investigation and discovered her birth certificate had been doctored and her adoptive mother had been put down as her biological mother.
"It was a huge blow," Ms. Madrigal said.
Ms. Madrigal has learned that her biological mother had got pregnant while having an affair with a married man and was punished by the regime — which had close ties with the Catholic Church — by having her baby taken away.
Ms. Madrigal accuses Dr. Vela of having forged her birth certificate.
In 2016, shortly before she died, Ms. Madrigal's mother, Inés, told an investigating magistrate she and her husband were unable to have children and Dr. Vela had given her the baby as "a gift" after a Jesuit priest acted as an intermediary.
In 2011 Antonio Barroso and Juan Luis Moreno revealed that in the 1960s they had been bought by their "fathers" from a priest in Zaragoza who was close to the Franco regime.
Mr Barroso, who founded the National Association for Irregular Adoption Victims (Anadir) believes 15 percent of adoptions in Spain between 1965 and 1990 were the result of babies being taken without consent from their biological parents.
Documents Finally Turned Over Last Year
Last year the Spanish Health Ministry and the Catholic Church handed over documents relating to thousands of babies which were stolen from hospitals in Spain over many decades.
The European Parliament had urged Spain to be more forthcoming and proactive in unearthing documents.
Franco came to power after the Spanish Civil War, which lasted from 1936 until 1939.
He led a military uprising against the democratically elected Republican government, which was supported by the Catholic Church and also by fascist Italy and Nazi Germany.
Franco refused to join the Axis powers during World War II and survived the fall of Mussolini and Hitler, preserving Spain in a fascist bubble well into the 1970s.
Democracy only returned to Spain in 1976, a year after Franco's death, and his Interior Minister Manuel Fraga Iribarne founded the Alianza Popular, which was renamed in 1989 the People's Party and is today led by Mariano Rajoy, who was ousted as prime minister earlier this month.