(CNN) We may never know why Jennifer and Sarah Hart's SUV plummeted 100 feet over a cliff, killing the couple and three teens. Or whether their three other children are dead or alive.

But new details about the mysterious family reveal a troubled history. Here's what we know about the couple and their six children:

The bodies of Jennifer and Sarah Hart and three of their children were found in and around their SUV.

All 6 children were adopted

Three of the children were adopted in Texas in 2006 -- siblings Abigail, Hannah and Markis, said Tiffani Butler of the state's Department of Family and Protective Services.

Then another trio of siblings were adopted in 2009 -- Sierra, Jeremiah and Devonte, Butler said.

It's unclear whether one or both of the Hart women adopted the kids.

In 2014, Devonte garnered national attention when he embraced a white police officer during racially charged protests.

Devonte helped quell tensions with his sign offering "Free Hugs," and his photo was shared around the world.

3 children remain missing

Nearly four years after that iconic photo, Devonte and two of his siblings are nowhere to be found.

After the family's SUV crashed on the Northern California coast, the bodies of Jennifer and Sarah Hart were found inside March 26. The bodies of Markis, 19, Jeremiah, 14, and Abigail, also 14, were found nearby.

But there was no trace of Devonte, 15, Hannah, 16, and Sierra, 12. Those children may have been left behind with friends, Mendocino County Sheriff Tom Allman said. Or they may have been killed when the SUV tumbled into the sea.

There were no skid marks

Perhaps the most troubling clue is what investigators didn't find.

JUST WATCHED Questions surround family killed off cliff Replay More Videos ... MUST WATCH Questions surround family killed off cliff 02:08

There were no skid marks or brake marks in the area leading up to the fatal crash.

And there were no witnesses to help guide police on what happened. The SUV was discovered only after a passer-by saw the mangled wreckage below the cliff.

Data from the vehicle's software air bag module and software suggest the car had stopped at the scenic highway outcrop overlooking the cliff and then accelerated off the road, said Greg Baarts of the California Highway Patrol's Northern Division.

And that leads police to believe the crash may have been intentional.

"At this point in our investigation, that is the direction we are going," Baarts said.

Where they were in the last days

Their car was found March 26.

Two days prior, the family had been in or around Newport, Oregon, according to the sheriff's office.

They are believed to have headed south on the US 101, reaching Mendocino County in California later that evening on Saturday, March 24.

Jennifer Hart stopped at a Safeway grocery store in Fort Bragg, California, which was captured on surveillance camera the following morning.

Authorities believe the family remained in the area until about 9 p.m. Sunday. After that, the sheriff's office said there's no further information about where they went before the incident.

Bruises discovered

Jennifer and Sarah Hart once lived in Minnesota, where Sarah Hart pleaded guilty to misdemeanor domestic assault involving one of the children in 2010, according to Douglas County court records.

That child had told an elementary school teacher of pain in her stomach and back, and bruises were discovered.

Sarah Hart told police she had spanked the child over the edge of the bathtub because of the child's behavior. She was sentenced to community service and one year of probation.

Then, about 10 months ago, the Harts moved into their home in Woodland, Washington, neighbor Bruce DeKalb said. He said the family was "very private."

Another neighbor, Bill Groener, said the children were home-schooled and kept inside most of the time.

Pleas for help

DeKalb said Devonte and one of his sisters had told him they were being mistreated. The neighbor recalled two disturbing encounters he had with the children.

"One of the girls came to the door at 1:30 in the morning and said that she needed help and the parents were not treating her properly, and (she) wanted us to protect her," DeKalb said.

(Devonte) started coming over asking for food and saying that they were taking meals away from him due to punishment. Neighbor Bruce DeKalb

"We ended up getting her back to her parents ... and then I went over there the next morning and just checked on things, and everything seemed normal, and we let it go from there."

DeKalb said Devonte was the only child he saw doing chores outside, such as taking the garbage bins to and from the street.

Then, starting about two weeks ago, Devonte "started coming over asking for food and saying that they were taking meals away from him due to punishment," DeKalb told HLN.

"It started out as one time a day and escalated up to three times a day, until a week went by and we decided that we needed to get professional help."

DeKalb said he called Child Protective Services on March 23, and officials arrived just after Jennifer Hart came home from work. But she didn't answer the door.

Sarah Hart came home soon after, DeKalb said. By the next morning, the family and their vehicle were gone.

Child Protective Services tried to visit the family twice more, on March 26 and 27, but couldn't make contact, the Washington State Department of Social and Health Services said.

The department said it had no prior history with the Hart family. But the search continues for the three missing children.</s>A Joshua Superior Court judge gave the Joshua Tree couple arrested late last month and charged with felony child abuse after their family was found living in squalid conditions a small victory after he ruled Tuesday, March 13, the couple will be able visit their children.

Attorneys for Daniel Panico, 73, and his wife, Mona Kirk, 51, argued the Department of Children of Family Services granted the parents permission to see their children during a hearing Friday in dependency court. They said the criminal protective order that had been issued barring the parents from having contact with their children — ages 11 through 14 — kept them from being able to comply.

“It’s a step in the right direction,” said Jackie Klear, a longtime friend and supporter of Panico and Kirk although she admitted she would have much preferred the protective order rescinded altogether.

During their last court hearing, March 6, Judicial Officer Joel Agron released the parents on their own recognizance from the San Bernardino County sheriff’s Morongo Basin station, but they are still facing three counts of felony child abuse charges. The couple’s attorneys argued that day Panico and Kirk didn’t pose a flight risk and couldn’t afford bail, which initially had been set at $300,000.

The family made national headlines when it was revealed their three children and Kirk slept in a plywood structure — which was approximately 20 feet long by 4 feet high by 10 feet wide — on the family’s 5-acre property in the 7000 block of Sun Fair Road in Joshua Tree, San Bernardino County sheriff’s officials said.

Their arrest sparked a debate surrounding homelessness and abuse with staunch supporters adamantly stating the couple loved and cared for their children but were targeted because they were poor.

The Sheriff’s Department, however, denies those claims and said the reason the couple was arrested was because of the conditions in which the children were forced to live for about four years.

Klear organized a GoFundMe account that raised more than $50,000 for the couple. A portion of that money went to buy Panico and Kirk a home, she said on social media posting.
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• California couple arrested after their 3 children found living in a wooden box Over the weekend, she shared photos on her Facebook account of friends and strangers coming together to clean up the two-bedroom home. They hope the judge Tuesday, will see the progress and remove the protective order and will allow the family to reunite.

“Last night we found the family a home to move into before we even start the purchase of the home. RENT FREE!!!,” Klear posted on the GoFundMe Friday. “Tuesday is their next court hearing here in Joshua Tree and because of all of you, they are going to walk into that courtroom showing that they have a new place to live with all their utilities on and such.”
A same-sex couple and three of their adopted children have been found dead at the bottom of a cliff at the coast of northern California, along with the wreckage of their SUV. After further investigation, authorities eventually deduced that it was very likely that the couple, which was previously known to have abused their children, intentionally drove off the cliff with them.