Inside the disturbing true story behind Netflix's The Asunta Case: Spanish couple murdered their adopted teenage daughter and lied about her being missing - before the 12-year-old's dead body was found with toxic levels of anxiety pills in her system

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The Asunta Case is Netflix's latest gripping true crime drama, which tells the tragic story of a 12-year-old girl who was murdered by her adoptive parents in Spain.

Starring Candela Peña and Tristán Ulloa as Alfonso Basterra and Rosario Porto - the killers - the six-part series is the gritty hard-hitting drama set to dominate the most watched list in the UK. 

But behind the glossy production are harrowing real life events that went down in history as one of the country's most disturbing crimes, which sent shockwaves across the world.

To this day, the motives behind the parents' harrowing actions remain a chilling mystery. 

The young victim, Asunta Fong Yang, was born in China and adopted by a wealthy Spanish couple in 2001 - when she was just nine months old.

Candela Peña and Tristán Ulloa star as Alfonso Basterra and Rosario Porto in Netflix's The Asunta Case

Basterra worked as a journalist - and Porto as a lawyer. The couple were well respected and connected in their home town of Santiago de Compostela in northwestern Spain.

On the surface, Asunta had a bright future to look ahead to with the love and support of her two parents. But behind closed doors, there was a much darker story - and it became clear in the events leading up to her death that something was deeply wrong.

The town welcomed Asunta and it originally appeared as if Basterra and Porto were loving parents to their adopted child, encouraging her to pursue her talents in music and dance.

The young girl was gifted, excelling in school and her hobbies, and moved ahead of her classmates by the time that she was in secondary school.

On September 13 2013, just days before she would have turned 13, Asunta was reported missing by her parents to Santiago police. A few hours later, her lifeless body was discovered on the side of the road.

Her parents were arrested shortly after Asunta's body was discovered, with Spanish police finding inconsistencies within Porto's story and suspecting Basterra was also involved.

Porto had told the police was that she left Asunta at their family apartment doing schoolwork at 7pm on the evening of her disappearance, and headed to her countryside residence around 20 minutes' drive away. When she returned a few hours later at 9.30pm, she claimed her daughter was gone.

However, CCTV footage showed Porto driving away from the apartment with a girl who had the same hair length as Asunta in the passenger seat during the time she had claimed the young girl was at home.

 Pictured: The real Rosario Porto being arrested at her adopted daughter's funeral after inconsistencies in her account of the night Asunta disappeared came to light

Netflix's dramatisation of Asunta's tragic case follows her childhood, where she seemingly enjoyed a happy family dynamic with her parents

 Alfonso Basterra and Rosario Porto (pictured being played by actors in the show) were well respected in their home town of Santiago de Compostela

Porto was arrested at her daughter's funeral. Following suspicions that the lawyer couldn't have acted alone, Basterra was arrested a day later. 

A harrowing picture of what was potentially going on behind closed doors began to emerge when forensic scientists discovered highly toxic levels of lorazepam - the main ingredient in the Orfidal pills that Porto was taking to ease her anxiety - in Asunta's system.

After Asunta's murder, more disturbing details began to emerge about her final months. Teachers at her music academy recalled how she turned up to classes looking spaced out and would often stumble, sometimes appearing as if she couldn't stand up straight.

She had also reportedly admitted to 'taking some white powders' when speaking to Isabel Bello who ran one of the academies, according to the Guardian.

Asunta allegedly then added: 'I don't know what they are giving me. No one tells me the truth.'

Journalist Alfonso Basterra (pictured) was detained on suspicion of murder on September 26 2013 in Santiago de Compostela

Rosario Porto was sentenced to 18 years in  Brieva prison in Spain (pictured in a file photo), where she died by suicide on November 18 2020 

This added to the case against Porto and Basterra, with scientists concluding after testing a strand of Asunta's hair that lorazepam had likely been present in her system for the past three months a least.

After Basterra and Porto's arrest, it was two years before the couple appeared on trial for their daughter's murder - a charge they were both found guilty of during a trial by jury.

In the years before the trial there was a media furore, with mass speculation over what happened to Asunta - but it was difficult for anyone to conclude exactly why her parents would commit such a heinous crime without an apparent motive.

In October 2015, Basterra and Porto appeared before a jury at The High Court of Justice of Galicia. Porto was unable to provide answers for why she lied about the events of December 13 2013, the night her daughter was reported missing. 

The father was also not able to explain his deeply suspicious actions in the lead-up to his daughter's death, which involved sourcing at least 175 Orfidal pills over 10 weeks.

Despite protesting their innocence, both of Asunta's parents were sentenced to 18 years in prison for their daughter's murder.

The new Netflix drama explores how investigators pieced together The Asunta Case, a seemingly motiveless crime 

Rosario Porto maintained her innocence regarding her daughter's murder until her death on November 18 2020. Pictured, a still from the Netflix series

Rosario Porto died by suicide on November 18, 2020 while she was imprisoned in the Brieva penitentiary in Ávila, Spain. 

Alfonso Basterra is still serving his sentence in Teixeiro prison in A Coruña, Spain. He is due to be released in 2033 but will be eligible for an 'open regime' within the Spanish prison system in 2025.

An open regime allows prisoners to have more contact with the public and leave the prison for several hours a day in order to work and attend personal appointments.

In 2017, Basterra sent a cryptic letter from prison to producers of the documentary Lo que la verdad esconde: el caso Asunta, which translates to Where the Truth Goes: the Case of Asunta, Spanish outlet El Correo reports.

He wrote: 'When I regain my freedom, I have the firm intention of disappearing, no one will hear from me again, not even Rosario Porto.

'I only have one reason to stay alive, which is none other than to be a free man again and reunite with my girl, never before.

There was a media frenzy surrounding The Asunta Case, with various theories on the motives behind Basterra and Porto's incomprehensible act. Pictured, a still from the series

While the dramatisation of The Asunta Case reveals details surrounding the case, there are still many questions left unanswered. Pictured, a still from the series

'In fact, I've already thought about how and where, I just don't know when, but everything comes [eventually].'

While Netflix's dramatisation of The Asunta Case has been fictionalised in parts, the plot largely stays faithful to the tragic real life story that's at its heart.

But while the new show may provide some more insights into the case, it looks likely that there will always be some unanswered questions.

To this day, the couple's motives remain unclear, though those involved in the investigation have their theories.

'I think they wanted to project the stereotype of a happy family,' said one investigator working on the case, as reported by the Guardian. 'If she wants something, she thinks she can just buy it.

'And if she doesn’t want it, she gets rid of it. He helps her to satisfy her whims. But when she is dependent, he becomes violent.'

But without a confession from Basterra and the impossibility of a confession from Porto, any insights into their motivation will largely be speculation.

Since Asunta's death, the Guardian reports that the adoption process in Galicia has become much stricter, with an exhaustive selection process for potential parents.

All six episodes of The Asunta Case are streaming on Netflix now.