(CNN)The mystery of what happened in the Hart family's fatal crash off a California cliffside remains under investigation.
Authorities now believe all 6 Hart children were in the SUV at the time of the fatal cliffside crash
But much of the family's troubled history leading up to that point is known, and it provides vital clues to understanding why Mendocino County Sheriff Tom Allman said he is investigating the case as a crime.
The bodies of Jennifer and Sarah Hart, both 38, were found inside their SUV March 26. The bodies of children Markis, 19, and Jeremiah and Abigail, both 14, were found nearby.
But there has been no trace of Devonte, 15, Hannah, 16, and Sierra, 12, and authorities now believe the three missing children were also in the vehicle.
An in-depth look at the Harts' past steps reveals a complicated picture of a couple with six adopted children, allegations of child abuse, an investigation from Child Protective Services and a fatal drive off a cliff.
Jennifer and Sarah Hart are a couple living in Minnesota.
Siblings Markis, Abigail and Hannah are adopted from Colorado County, Texas, according to Tiffani Butler of the state's Department of Family and Protective Services.
It's unclear whether one or both of the Hart women adopted the kids.
Police in Alexandria, Minnesota, receive a call about a 6-year-old child, whose name and gender is redacted, with a bruise on the left arm, according to Alexandria police records. The child indicated to staff that the mother, Jennifer Hart, struck the child's arm with a belt.
Police and social services interview the Hart parents.
"They say (the child) has been constantly going through food issues, where (child) will steal people's food at school or eat out of garbage cans or off the floor," according to the police report.
The parents also say they do not know how the bruise got on the child's arm, but the state says that the child had fallen down eight stairs in the house a few days earlier.
The case is closed from a legal standpoint, according to the police report.
Siblings Jeremiah, Sierra and Devonte are officially adopted from Harris County, Texas, Butler said.
In adoption cases, children live with the potential legal guardians for six months before adoption goes through. Again, it's unclear whether one or both of the Hart women adopted the children.
In Minnesota, one of the Hart children tells an elementary school teacher of pain in her stomach and back, and bruises are discovered.
Sarah Hart tells police she spanked the child over the edge of the bathtub because of the child's behavior.
She is charged with malicious punishment of a child and misdemeanor domestic assault, according to Minnesota court records.
Sarah Hart pleads guilty to misdemeanor domestic assault involving one of the children, and officials dismiss the malicious punishment of a child charge, according to Douglas County, Minnesota, court records.
She is sentenced to community service and one year of probation.
Devonte Hart, then 12, cries as he hugs a white police officer during a Black Lives Matter protest in Portland, Oregon, following a grand jury's decision not to indict the white officer who killed Michael Brown, an unarmed black man, in Ferguson, Missouri.
A photo of that hug goes viral, and The Oregonian newspaper calls it "the hug shared around the world."
The Hart family moves to a home in Woodland, Washington, neighbor Bruce DeKalb said.
The family is "very private," he said.
One of the Hart children tells DeKalb that she is being mistreated by her parents.
"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.
"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."
Devonte begins "coming over asking for food and saying that they were taking meals away from him due to punishment," DeKalb said.
"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," he said.
DeKalb calls Child Protective Services to check on the Hart family. Officials arrive just after Jennifer Hart comes home from work, but she does not answer the door.
Traveling in a 2003 GMC Yukon XL, the Hart family is in and around Newport, Oregon, around 8:15 a.m., according to police.
They drive south along US 101 until they reach Leggett, California, and then travel south along state Route 1 until reaching Fort Bragg around 8 p.m. They remain in Fort Bragg for about a day, authorities said.
Jennifer Hart is seen on surveillance footage shopping at a Safeway in Fort Bragg. The family remains in the area until about 9 p.m., authorities said. Their movements at that point are not known.
A welfare check is conducted at the Hart family home at the request of the Cowlitz County, Washington, Child Protective Services, but no one answers the door.
The Hart family SUV is seen upside down on the rocky shoreline at the bottom of a 100-foot cliff along a remote stretch in Mendocino County, California, about 180 miles north of San Francisco. A passer-by calls authorities to report the crash.
The bodies of Jennifer and Sarah Hart are found dead in the vehicle. Three of their children, Markis, Jeremiah and Abigail, are found dead outside the car.
The vehicle had to have traveled 75 to 100 feet on a dirt turnout next to the highway before it went over the cliff edge, officials said. There were no skid or brake marks, said Allman, the Mendocino County sheriff.
The vehicle was in the water for at least several hours before its discovery, Allman said.
Upon learning that three other children are unaccounted for, officials launch a further search-and-rescue effort along the ocean waters to locate Hannah, Devonte and Sierra.
California Highway Patrol launches a fixed-wing airplane and helicopter, and the US Coast Guard brings a rescue boat to the area.
A second welfare check at the Hart home reveals pets inside and conditions that show the trip was temporary, according to Clark County, Washington, sheriff's Sgt. Brent Waddell.
Allman, the Mendocino County sheriff, says there is "every indication" all six children were in the SUV when it went over the cliff, though he says it's possible the three missing children were left with friends.
"We have no evidence and no reason to believe this was an intentional act," Allman says.
Police conduct a search warrant at the Hart family home in Washington state and seize a laptop and iPad.
In the affidavit requesting the search warrant, a Clark County sheriff's deputy says he is seeking evidence on what happened to the family, including possible suicide notes.
California Highway Patrol's investigators believe "a felony has been committed," the affidavit says.
Authorities say publicly they believe the crash may have been intentional, according to Greg Baarts of the California Highway Patrol's Northern Division.
Preliminary data from the air bag module and the car's software indicate the vehicle stopped at the turnout and then accelerated for about 70 feet off the cliff, Baarts says.
Searches of the area continue for the next few days, but Devonte, Hannah and Sierra remain missing.
A large-scale search and rescue operation continues, with about 80 people combing the surrounding area of the crash.
Allman tells HLN that Jennifer Hart was driving the SUV when it went over the cliff.
"I'm to the point where I no longer am calling this an accident. I'm calling it a crime," Mendocino County sheriff tells HLN.
The Mendocino County Sheriff's Office clarifies that Jennifer and Sarah Hart were not wearing seat belts, contrary to previously reported information.
The search for Devonte, Hannah and Sierra Hart is suspended due to heavy rain expected for the next few days, and authorities announce the three are believed to have also been in the SUV at the time of the crash.
"Information obtained through interviews with family and friends indicated it was rare for the family to be apart, especially while traveling," a news release from the sheriff's office says. "That information coupled with the other children being recovered outside of the vehicle ... supports the possibility that the missing children were swept away from the crash scene by the Pacific Ocean."