THE six Hart children who died when one of their lesbian mothers drove off a cliff in California were severely malnourished, neglected and abused, welfare records reveal.

Child protection officers began investigating the mothers Jennifer and Sarah Hart, both 38, as far back as 2013 when the adopted children, Jeremiah, Ciera, Devonte and biological siblings Hannah, Markis and Abigail, were aged between eight and 15.

Five of the six children were so small in 2013 that their heights and weights were not listed on growth charts for children their age, Oregon Livereported.

Authorities believe it was Jennifer who intentionally drove the family SUV over a cliff last month, killing the entire family.

Preliminary toxicology reports found that Jennifer was drunk at the time she drove at 145km/h over the edge of the Pacific Coast Highway near Westport, 250km north of San Francisco.

None of the occupants were found to be wearing a seatbelt; the bodies of Devonte and Hannah have not been recovered.

Department of Human Services files from when the couple lived in Oregon and Minnesota reveal Sarah and Jennifer were regularly accused of withholding food from the children.

A Minnesota welfare worker estimated the size of Abigail Hart when aged six as that of a two-year-old.

Abigail’s Minnesota school contacted child protective services when the girl was seen rummaging through garbage in search of food.

One woman contacted authorities to report that when she questioned Jennifer Hart about the paucity of food given to the children, Jennifer claimed daughter Hannah was morbidly obese when adopted.

The girl 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”.

When the woman made the complaint, authorities noted in its records that Hannah was “very small” and had missing front teeth.

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

When Jennifer realised the next day that the entire pizza had been eaten, she became enraged and took all the children into a bathroom.

The woman said the kids would not answer a question without looking at Jennifer first, and seemed “lethargic”.

A Minnesota case worker reported that all six children denied being abused by their parents.

In near identical accounts, each of the children said instead their mothers disciplined them by making them meditate.

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

One of the women said Markis was punished on his July 1 birthday by the mothers forbidding anyone to wish him “happy birthday”, Oregon Live reported.

Jennifer told the woman that Markis had tried to kill her and Devonte Hart had to save her.

A Minnesota child protection officer wrote in a report that Jennifer and Sarah knew how to blame apparent red flags on the children.

When Oregon welfare workers interviewed the two women about the complaints, Jennifer said the kids were thriving at home.

They said many of the complaints were because people did not understand her family’s “alternative lifestyle”.

The apparent murder-suicide carried out by Jennifer Hart came days after a social worker visited the family in Washington state to investigate a complaint that the children were being neglected.

At the crime scene, Californian police reported there were no skid marks and the vehicle was at a full stop before accelerating off the cliff.

Preliminary reports said the SUV had stopped about 20m from the cliff’s edge, then sped off.

Following the crash, only three of the children’s bodies were found.

But the body of 12-year-old Ciera Hart, the youngest child, was found off the northern Californian coast earlier this month.

Searches in the waters off northern California continue.