Capt. Greg Baarts with the CHP Northern Division says information pulled from the SUV's software shows the vehicle was stopped at the highway pullout before it accelerated straight off the cliff.
Baarts says the electronic information combined with the lack of skid marks led officials to believe it was intentional.
A Mendocino County Sheriff's Office spokesman says authorities believe at least one felony was committed but declined to specify.
Five members of the Hart family - a free-spirited brood from Washington state who grew their own food and took up activist causes - were found dead. Searchers kept looking Friday for three more children believed to have been in the vehicle when it went over a scenic coastal overlook and landed on rocks in the Pacific Ocean below. The missing children may have been washed out to sea.
Known as the Hart Tribe, the multiracial family of two married women - Sarah and Jennifer Hart - and six adopted children took spontaneous road trips to camp and hike and traveled to festivals and other events, offering hugs and promoting unity.
One of the children, Devonte Hart, drew national attention when the black youngster was photographed hugging a white police officer during a 2014 protest in Portland, Oregon, over the deadly police shooting of a black man in Ferguson, Missouri. Devonte was holding a "Free Hugs" sign.
A passing motorist discovered the wreck on March 26, three days after social service authorities opened an investigation apparently prompted by a neighbor's complaint that the children were being deprived of food.
A state caseworker went to the Harts' house in Woodland, Washington, on March 23 but didn't find anyone home, officials said. The Department of Social and Health Services had no prior history with the family, said Norah West, an agency spokeswoman.
Bruce and Dana DeKalb, next-door neighbors of the Harts, said they called child protective services because 15-year-old Devonte had been coming over to their house almost every day for a week, asking for food.
Dana DeKalb said Devonte told her his parents were "punishing them by withholding food." The boy asked her to leave food in a box by the fence for him, she said. She told The Oregonian/OregonLive that Devonte asked for things like tortillas and peanut butter and eventually was coming over three times a day.
She said the boy's first words when he came to the door March 22 were: "Have you called?"
"I almost got the feeling it was more of, 'What are you waiting for, lady?" Dana DeKalb said.
Authorities don't know exactly when the wreck took place. But by Saturday, the family's SUV was gone from the driveway, Bruce DeKalb said.
Well before the wreck, Sarah Hart pleaded guilty in 2011 to a domestic assault charge in Douglas County, Minnesota, telling authorities "she let her anger get out of control" while spanking her 6-year-old adoptive daughter, court records show.
The two women, both 38, were found dead inside the SUV, while three of their children - Markis Hart, 19, Jeremiah Hart, 14, and Abigail Hart, 14 - were discovered outside the vehicle. Searchers were looking for Hannah Hart, 16; Sierra Hart, 12; and Devonte.
Their model of Yukon was presumably equipped with a black box recorder that would show its speed and use of the brakes, said Marcus Mazza, an engineer and accident-reconstruction expert with Lancaster, Pennsylvania-based Robson Forensic.
Authorities in Washington state searched the family's home Thursday. The Clark County sheriff's office said deputies were looking for bills or anything else that could shed light on why the family left and other circumstances related to the trip, Portland, Oregon, news station KGW-TV reported.
Family friend Max Ribner took issue with the notion the wreck was something other than a tragic accident. The couple adopted many of their children from "hard backgrounds," he said. "They transformed these kids' lives."