Updated

Authorities are retracing the route the doomed Hart family traveled before plunging off a California cliff last week, as officials continue searching for three of the children, who are presumed dead but who were mysteriously absent from the family's battered SUV.

Devonte Hart, 15, Hannah Hart, 16, and Sierra Hart, 12, were reported missing March 26 after the family’s SUV was found overturned at the bottom of a cliff just off the Pacific Coast Highway, about 150 miles north of San Francisco.

"The search for the additional three children belonging to the family continues both at the scene, through water rescue and recovery, and other locations including routes of travel," the California Highway Patrol said in a Monday news release, according to Oregon Live.

hart family california cliff crash

The Hart family was killed after their SUV plunged off a cliff near San Francisco. (AP)

Authorities had said they believe all six adopted children of Jennifer and Sarah Hart, both 38, were in the SUV at the time of the crash. The bodies of both parents and three children — Markis Hart, 19; Jeremiah Hart, 14; Abigail Hart, 14 — were found at the scene when authorities found the vehicle.

The search for what caused the deadly crash has led investigators to examine “red flags” in the Harts’ past. Investigators believe the incident may have not been an accident — as originally thought — after evidence suggested the driver, Jennifer Hart, accelerated off the side of the road.

AUTHORITIES INVESTIGATE CALIFORNIA CLIFF PLUNGE AS A FELONY

Court documents stated the speedometer of the SUV was pinned at 90 mph, though authorities warned the device could have been altered at impact.

“At this point we think a felony was committed,” Officer Olegario Marin, a spokesman for the California Highway Patrol’s Ukiah office, told the San Francisco Chronicle on Monday. “We’re investigating all aspects of the incident and believe it was possibly an intentional act.”

california cliff crash

Authorities are retracing the route the Hart family took before they died in a car crash. (AP)

Capt. Greg Baarts of the California Highway Patrol said the SUV had stopped at a pull-off area before the crash.

Bruce and Dana DeKalb, the next-door neighbors of the Harts who lived in Woodland, Wash., previously said they called Child Protective Services two days before the family was found dead because they thought Devonte was going hungry. They said Devonte — who gained nationwide fame after a photo of him at a 2014 Portland, Ore., rally holding a “Free Hugs” sign went viral — had been coming over to their house too often in the past week asking for food.

The Dekalbs also recounted one of the girls rang their doorbell at 1:30 a.m. in August 2017 asking for protection.

“[She] was at our door in a blanket saying we needed to protect her," Bruce DeKalb said. "She said that they were abusing her. It haunted my wife since that day."

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Devonte Hart, who was then 12, was photographed at a rally in Portland, Ore. in November 2014. (AP)

FAMILY KILLED IN CALIFORNIA CLIFF CRASH HAD RECENT VISIT FROM CHILD PROTECTIVE SERVICES, POLICE SAY

Authorities attempted to reach the family three times and made their third attempt the day after their SUV was found. Signs showed the family planned for a short trip.

Despite relatives and friends calling the family “radiant, warm adventurous inspiring people,” Baarts said investigators’ interviews with them showed “there have been red flags.”

Investigators last week obtained a search warrant for the family's home in Woodland and looked for itineraries, bank and phone records, credit card receipts, journals or other documents that might shed light on the case.

The Associated Press contributed to this report.