The scene unfolds before a stunned, disbelieving public: A seemingly idyllic family is gone in a flash of violence.

It has played out numerous times just in the Northwest. In 2001, Christian Longo drowned his wife and three children in coastal Oregon rivers In 2002, Edward Paul Morris killed his pregnant wife and their three children, leaving their bodies in the Tillamook State Forest. And in 2017, Keith Kroeker bludgeoned his wife to death before shooting his three children and committing suicide as the family's rural Marion County homestead burned around them.

Now, the Hart family – mothers Jennifer and Sarah and their six children -- appears to be the latest. Five members of the Oregon clan, which had recently moved from West Linn to Woodland, Washington, were found dead at the bottom of a California cliff, and three kids remain missing. Officials suspect the crash was intentional.

If the investigation confirms the suspicion, the case would be the latest example of what criminologists call family annihilators, cases in which family members kill an intimate partner and their children. Those left behind – family, friends, the public – are left to wonder what would drive a person to commit such a ghastly crime.

Domestic violence experts and criminologists say the circumstances surrounding the Hart family's crash appear to be unusual. Guns are overwhelming used by family annihilators, but driving a vehicle off a coastal highway was described as "bizarre" by one researcher.

The story does, however, bear at least one hallmark of some other mass family killings: The Harts had a documented history of child abuse, and experts say it's likely there was an undercurrent of spousal violence as well. Also, as in the Kroeker slayings, a common thread could be present: No clear motive may ever emerge.

The overwhelmingly majority of these massacres are committed by white men in the 30s and 40s, according to domestic violence experts. And that is what sets the Hart deaths even further apart: A lesbian couple, beloved and admired in the community, raising six adopted black children.

The Mendocino County Sheriff's Office said this week it is treating the incident as a crime, and its top official hinted authorities are close to considering it a homicide investigation. Authorities have said Jennifer Hart was the driver.

Meanwhile, a trail of troubling child abuse reports in multiple states indicates the nontraditional family wasn't what it outwardly appeared.

David Adams, co-executive director of a Massachusetts-based domestic violence counseling and education center, said initial findings suggest it's unlikely the crash was an accident or a shared action between Jennifer and Sarah Hart.

"It's far more likely that this was a unilateral decision by the abusive partner to take out the whole family, basically," he said, noting that he was speaking based on his general knowledge and he didn't know the family.

Hannah Scott, a professor of criminology at the University of Ontario Institute of Technology, said she published the only study specifically looking at female family annihilators.

Men are typically fueled by revenge or anger, Scott said. Financial crises, domestic violence and a recent divorce or estrangement are often cited as factors. That's not true for women. Mental illness or a reaction to years of battery or abuse are more commonly present, as are premeditated family slayings.

In 2014, Jessica Smith drowned her two-year-old toddler at a Cannon Beach hotel and tried to kill her 13-year-old daughter. Smith is an outlier in the family annihilator profile as she did not try to kill her husband, whom she was estranged from and who had a temporary restraining order against her. Smith was sentenced to life in prison despite claiming she had no recollection of the murder.

Scott's study documented just seven female annihilators over 40 years in the U.S. "Real or imagined concerns about losing custody of the children may also be a trigger for female family annihilators," the study found.

One area researchers have studied is post-partum depression and women who kill their infants. Women are more likely to kill children under the age of one than men, research shows.

Scott said researchers should more deeply look at same-sex relationships and domestic violence. "It's an area that is understudied," she said.

Gender aside, most abusers share a similar trait.

"It's important for abusers to manage their identity," Scott said. "It was very important that they look good outside their family."

Jennifer Hart, the family's primary caretaker and the main social media architect, frequently shared lengthy posts on Facebook or videos on YouTube.

Family friends said the Harts became more isolated in the years after son Devonte's photo hugging a Portland police officer went viral. The latest investigation into abuse was opened days before the family SUV was spotted 100 feet below Highway 1 in Mendocino County on March 26.

Adams agrees public perception is critically important to abusers. "They tend to live and die for their image. Their solution is to also spare their families" the humiliation [of living with a damaged image] "They actually feel that they are saving them."

Jacquelyn Campbell, a professor and researcher at Johns Hopkins University's School of Nursing, said she was stunned and saddened to read about the Hart family's fate. As of Friday, authorities haven't located the bodies of three of the children, including Devonte, but they believe the family was all in the vehicle together and the bodies may have washed out to sea.

Campbell said data from a 1990s era analysis from 12 cities found nine instances of women killing an intimate partner of the same gender out of a dataset of 307 murder-suicides, an indication of the limited study involving same-sex partners.

She said domestic violence "frequently" accompanies child abuse. "When you have both, you have to deal with both in sensitive ways," she said.

Campbell said in most cases of domestic violence and child abuse, there is no "monster." Abusers often hurt loved ones because of trauma in their own childhood.

She thinks society needs to do a better job of prevention by offering support, rather than relying on punishment after the fact.

"There's somebody that is using violence that needs to be helped to stop using violence," she said, "so we can prevent these kinds of tragedies."

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-- Andrew Theen

atheen@oregonian.com

503-294-4026

@andrewtheen