SUV's plunge off cliff that killed California family may have been intentional act: Police

The crash which claimed the lives of a family of eight in California last week may not have been an accident, according to the California Highway Patrol.

The entire Hart family is presumed dead after its SUV plunged off a cliff March 26 on the Pacific Coast Highway.

According to the CHP, which said in a conference call with reporters Sunday it had completed its initial review of the crash, software pulled from the SUV shows it was stopped at a pull-off spot on the side of the highway before accelerating straight ahead off the cliff. No skid marks were found on the road at the spot it plunged over the edge and police said the brakes were never applied after leaving the gravel pull-out spot.

"Preliminary investigation indicates to us that this incident might have been an intentional act and not the result of a traffic collision," Acting Assistant Chief for the CHP Greg Baarts said.

Baarts said the speedometer in the car was "pinned" at 90 mph when they recovered it at the bottom of the cliff near Mendocino, California.

"The most-likely cause for that reading is the shock from the impact," Baarts said. "So whenever a vehicle slams into something it's fairly common the speedometer will lock at a certain speed. But you cannot use that information [except] for a base, just for the speed of the vehicle. There are several other factors that need to be considered."

Jennifer Hart and Sarah Hart, a married couple who adopted six children, were both found dead at the vehicle along with three of the children: Markis Hart, 19, and Jeremiah and Abigail Hart, both 14. Devonte Hart, 15, Hannah Hart, 16, and Sierra Hart, 12, are still missing, but officials presume they were also killed in the accident.

"We're going under the assumption at this point that Devonte, Hannah and Sierra were in the vehicle, but we don't have 100 percent information," Capt. Greg Van Patten from the Mendocino County Sheriff's Office said.

Van Patten said the area where the SUV crashed has been difficult to search, with unpredictable tides and murky waters making divers unable to go in the ocean.

An image of Devonte Hart garnered national attention in 2014 when a photographer snapped a photo of him hugging a police officer with tears streaming down his face during a protest in Portland, Oregon, over the police killing of Michael Brown.

Since the accident, information has emerged that Jennifer and Sarah Hart, both 39, had been investigated over the treatment of their children.

A 2010 complaint filed in Douglas County, Minnesota, revealed that Sarah Hart was charged with malicious punishment of a child and domestic assault after a 6-year-old child showed a teacher bruises on her stomach and back. Court documents show that Sarah Hart was convicted on the domestic assault charge, but the charge of malicious punishment of a child was dropped.

In mid-March, Child Protective Services in Washington received a call about neglect and abuse by the Harts, spokeswoman Norah West said in a press conference March 29. The agency attempted to make contact with the family in person on Friday, March 23 as well as last Monday and Tuesday, West said.

Alcohol and toxicology reports are expected to take four to six weeks to come back, Van Patten said.

No suicide note has been found, police said.

CHP investigators have also acquired search warrants to look through the Hart's cellphone and bank records for clues into why the crash might have been intentional.

ABC News' Julia Jacobo contributed to this report.