WILLITS, CALIF. -- Sarah Hart had a toxic level of Benadryl in her system when the SUV carrying her family plunged off a California cliff last year, the doctor who performed her autopsy testified Wednesday.

At least three of her children also had elevated levels of the drug in their systems, but their levels were less than toxic, Dr. Greg Pizarro said during the first day of a coroner's inquest into the deaths of Sarah and Jennifer Hart and their six adopted children, ages 12 to 19.

The proceedings will continue Thursday when the lead investigator testifies about the evidence he has compiled in the months after the crash.

A tourist tipped off authorities to the wreckage of the family’s GMC Yukon at the bottom of an oceanside cliff on March 26, 2018. Emergency responders discovered five bodies in or near the overturned SUV at the edge of the surf.

The SUV was found below a wide scenic lookout point less than 15 miles north from where Jennifer Hart was last spotted buying food in the city of Fort Bragg. It remains unknown whether authorities ever learned the exact reason she drove over the cliff’s edge.

Emergency responders found the mothers' bodies and those of Markis, 19, Abigail, 14, and Jeremiah, 14, soon after the crash. They found 12-year-old Sierra's body in the weeks after the crash. A foot belonging to 16-year-old Hannah was found later that spring. No trace of Devonte, 15, has ever been found.

Pizarro, a forensic pathologist who has autopsied hundreds of bodies for Mendocino and other California counties, discussed his autopsies of Jennifer and Sarah Hart and four of their children. He said he found no injuries to indicate that anyone except Jennifer Hart was wearing a seat belt when the SUV slammed into the rocks.

He said he believes all died almost instantly after the crash from spinal injuries they received upon impact. The body of the Hart’s youngest daughter, Sierra, was found two weeks after the crash and was too decomposed to make a conclusive determination, he said.

Mendocino County deputies began investigating the crash as a crime after they observed there were no skid marks where the car went off the cliff.

The case has brought national attention to Mendocino County, a county of 88,000 a two hour's drive north of San Francisco. Mountain ranges dot the terrain and open up to the Pacific Ocean coastline where the Hart family died.

About 30 people, almost all police, attorneys and reporters, attended the first day of the inquest at the Willits Justice Center, a building that also houses the town’s police force and sits next to the city hall. More than 300 people tuned in to the testimony being livestreamed on YouTube.

Officials expect the proceeding to conclude by Friday after a jury of 14 people returns with eight separate conclusions about the manners of death for each family member.

The inquest also has another purpose: to make public the evidence gathered during the investigation. It is the first public forum in which authorities plan to tie together evidence collected by three different law enforcement agencies in two states.

Attorney Matthew Guichard, hired to oversee the hearing, guided the testimony of six officials by asking a list of questions he wrote after reading police reports.

In addition to Pizarro, two California Highway Patrol officers, a Mendocino County sheriff's deputy, the county's search and rescue coordinator and a detective from Clark County, Washington, testified about what they found in the days and weeks after the crash.

The family lived in the Portland area during the final five years of their lives, first in Wilsonville and then in rural Clark County north of Vancouver.

Clark County Sheriff’s Office Detective Adam Beck discussed the evidence that his agency had previously disclosed in response to public records requests. He also disclosed that searches of the family’s bank records turned up nothing significant that would indicate they were planning to take a long trip.

Three more investigators will take the stand tomorrow. No one has yet said what information was found on the laptops, iPad, flash drives and at least one cell phone authorities collected after the crash.

Pizarro, the forensic pathologist, revealed toxicology results from the five first Hart autopsies he conducted, but not from his examination of Sierra’s body, as it had spent weeks in the ocean. Any evidence that she had diphenhydramine, the active ingredient of Benadryl, in her system would have washed away, he said.

Her siblings Markis, Abigail and Jeremiah, who were found near the SUV, all had levels of the drug in their system that was significantly higher the therapeutic range, Pizarro said.

He described the level of Benadryl in their mother Sarah Hart’s system as toxic. She may have been drowsy, hallucinating and experiencing heart palpitations or tremors, Pizarro said.

Toxicology tests showed Jennifer Hart had an elevated level of alcohol in her system, 0.102 percent, above the legal limit for driving, Pizarro said.

Days before the crash, Washington child welfare officials were called to the family’s home to investigate reports that food was being withheld from the children.

In reference to a question about Markis and Abigail, Pizarro said he did not see any signs the children were malnourished.

“They didn’t look like they were emaciated,” he said.

He did not state the children’s heights, nor did he note that Markis’ and Jeremiah’s weights put them in the bottom 10 percent of young men their ages and that Abigail’s weight was too low to be listed on the growth chart for girls her age.

He described all of the children’s injuries as consistent with being in a high-speed, rollover crash.

Jennifer Hart also had many external injuries, he said. It’s impossible to know what injuries she sustained in the crash and what injuries occurred after her body fell out of the SUV onto the rocky coastline as authorities towed it up the cliff, Pizarro said.

Mendocino County Deputy Sheriff Robert Julian said he saw Jennifer Hart's body and a backpack fall out of the wreckage. The bag contained at least one cell phone, flash drives and credit cards belonging to the couple, he said.

Sarah Hart's body was pinned inside the wreckage between the passenger seat and the roof, said California Highway Patrol Officer Michael Covington.

In the next days, dozens of volunteers returned to the coast to search for the bodies of the three children that were missing, said Jared Chaney, commander of Mendocino County’s search and rescue team.

Searchers worked with the U.S. Coast Guard to estimate where the bodies had likely floated. At one point, more than 85 people from search and rescue teams across California collectively combed a miles-long expanse. The crews used high-powered telescopes, drones, divers and people specially trained to climb dangerous terrain. They also used dogs trained to find people and human remains.

Ocean waters washed new debris onto the beach and out to sea every day, Chaney said, complicating the search. "Every tide period would reset the beach," he said.

Crews never found any human remains. Chaney said beachcombers found the body of Sierra Hart on a beach north of the crash site. Another person located a foot belonging to her sister Hannah Hart more than a month later.

At first, the person thought they had located a shoe attached to part of a pair of pants. But that person’s dog would not leave the objects alone, and officials later discovered the foot inside, Chaney said.

This story was updated with additional information about Wednesday’s testimony.

-- Molly Young

myoung@oregonian.com