When news that a family of eight had plummeted to their deaths over a cliff last year, hearts across the world shattered.

It appeared they were on a family roadtrip when the car veered off the road and over the cliff. A tragic accident.

The Harts were, after all, what seemed like the perfect family – the six adopted children aged 12 to 19 were regularly seen grinning widely in gushy social media posts shared by their mothers Jen and Sarah.

The were a left-wing, socially conscious couple who often took their children to protests, music festivals and liberal events.

But beneath the idyllic veneer, they were far from the caring and thoughtful parents they painted themselves as.

A month on from what the world believed was a devastating accident, it was discovered that all eight deaths were far from an accident.

In a sickening twist, one of the children's mothers, Jen, had deliberately driven her SUV over a 30-metre cliff with her wife and all six children inside. A murder-suicide.

And now - in a true crime podcast tipped to be the next Teacher's Pet, the chilling backstory of the slain family - and how the children were ultimately failed by the system - has been revealed.

Broken Harts is a follow-on from Glamour's long-read piece on the case by reporter Lauren Smiley. It follows the events leading up to trip that claimed the lives of the Hart family, from child abuse allegations, claims of racism to continual neglect.

The "accident".

On March 26, 2018, German tourists spotted a family-sized SUV car turned upside down at the base of a 30-metre cliff in Mendocino, California. Inside were the bodies of driver Jennifer Hart, 38 and her wife Sarah Hart, also 38.

The bodies of their adopted kids Markis, 19, and 14-year-olds Jeremiah and Abigail, were located close by, while the body of 12-year-old Ciera Hart washed ashore on April 7.

The Harts' other adopted children Devonte, 15, and Hannah, 16, have never been found, but it is believed they were also in the car at the time of the crash.

At the crime scene, Californian police reported there were no skid marks on the road indicating an attempt to avoid the crash. Instead, the vehicle was at a full stop before accelerating off the cliff.

Toxicology reports also found Hart was under the influence, and that none of the occupants were wearing seatbelts.

On April 6, Mendocino County Sheriff Tom Allman declared: “I’m to the point where I no longer am calling this an accident. I’m calling it a crime.”

The crime, known as a “family annihilation”, shocked friends of the Harts, who had seen nothing but glowing social media posts depicting a loving family.

The apparent murder-suicide came days after a social work visit at the family's Washington home. It had been triggered by a complaint that the children were being neglected.

The coroner's inquest.

More than a year after the Hart family died, on April 3 and 4, 2019 a coroner's inquest took place to officially determine if their deaths were murder-suicide, accidental or undetermined. The inquest, which has attracted much public attention and intrigue, was live-streamed by the county sheriff's office.

Forensic pathologist Dr. Greg Pizarro testified that Jennifer Hart's blood alcohol level far-exceeded the California limit and tested at the equivalent of about five beers. He testified that Sarah Hart had a high level of benedryl in her blood stream: She would have had to have taken 42 single doses to reach this near toxic level, but this was not the cause of her death.

At least three of the children also had elevated levels of the drug. No one in the car was believed to be wearing a seatbelt.

The inquest heard that Google searches recovered from Sarah Hart's phone revealed a premeditated plan: While on the road, Sarah had Googled questions surrounding drug intake, overdosing and drowning, investigator Jake Slates testified.

On Thursday, the jury took less than an hour to deliver their verdict: Jen and Sarah Hart had died by suicide. Their six adopted children died "at the hands of another".

Welfare records.

After their deaths, the family's dark past was uncovered through welfare records.

Deeply concerning reports show the children were severely malnourished, neglected and abused by their mothers, who had been investigated by child protection officers on many occasions, from as far back as 2013.

In a heartbreaking discovery, in 2013, five of the six children were so small that their heights and weights were not listed on growth charts for children their age, Oregon Live reported. It was later found that the mothers would regularly withhold food from their children - claiming that they were keeping them from obesity.

At six years old, Abigail Hart was found rummaging through the garbage for food by her Minnesota school. She was reported by welfare workers to be the size of a two-year-old.

One woman also contacted authorities to report that when she questioned Jennifer about how much she was feeding her children, Jennifer claimed daughter Hannah was morbidly obese when adopted.

Hannah was adopted in 2006 as a four-year-old and Facebook photographs of her with siblings Markis and Abigail show a normal-sized girl.

But Jennifer insisted to the woman that Hannah was "so much better now". On investigation into the complaint, authorities noted that Hannah was "very small" and had missing front teeth.

Friends recount dark tales.

Another friend told authorities that when the family had stayed with her, the children were only allowed to eat a tiny slice of pizza each, alarming her immediately.

The next day, when Jennifer realised the entire pizza had been eaten, she was furious, and took all the children into a bathroom to get to the bottom of who had eaten more than their allocated amount.

The woman said the children would not answer a question without looking at Jennifer first, and seemed "lethargic" throughout the stay.

The lies.

Time and time again, all six children had denied being abused by their mother.

In near identical accounts, each of the children instead told authorities their mothers peacefully disciplined them using meditation.

Case workers in Oregon, however, reported Hannah and Markis, the eldest of the children, were the targets of Jennifer's abuse, according to two women who had contacted children's services.

One of the women said Markis was punished on his birthday by his mothers, who forbade anyone from wishing him "happy birthday", Oregon Live reported.

To explain her treatment of Markis, Jennifer told the woman he had tried to kill her and Devonte had to save her.

A Minnesota child protection officer wrote in a report that Jennifer and Sarah became skilled at dodging complaining. They knew exactly how to blame apparent red flags on the children to avoid further scrutiny of their parenting.

Jennifer claimed each time a complaint was made that the kids were thriving at home, but, in a sign of her manipulation skills, would convince welfare workers that people simply did not understand her family's "alternative lifestyle".

Broken Harts by iHeartRadio & Glamour is available to stream on Apple Podcasts.