The Mendocino County Sheriff said during a Friday news conference that the body was found about 7 miles south of where the Thottapilly family's vehicle is believed to have gone off an embankment. California drivers are deemed drunk having a level of 0.08 or higher.
But their three other children - Devonte, 15, Hannah, 16, and Sierra, 12 - are missing, officials said.
On April 7, vacationers spotted a body floating in the Pacific Ocean surf near the site of the crash. He also said that before the crash, the family had stopped in Naselle, Wash., about a 90-minute drive northwest of Woodland, Wash., where they lived.
"Friends of [my mom's] and friends of mine, are all calling to say, 'Can we come and say goodbye to the house?' - not wanting to buy it, not want to come through open houses, just see the family, see me and say goodbye to the house".
Toxicology checks also discovered that their spouse Sarah Hart and two of their children needed "a significant quantity" of a component commonly seen in the allergy drug Benadryl, that could make people drowsy.
No one in the vehicle, a GMC Yukon, was wearing a seatbelt, Captain Carpenter said on Friday. "The Coroner's Division is still awaiting the BA/Toxicology analysis of the third child that was recovered on March 26".
"Because fo the time in the ocean, the facial features were not there to allow the [biological] family to identify", Allman said.
Two of the Hart children whose bodies have been recovered also had diphenhydramine in their system.
A neighbor of the Harts in Woodland, Washington, had filed a complaint, saying the children were apparently being deprived of food as punishment. Investigators could not immediately identify the body, though it appeared be an African-American girl's body.
News reports had previously indicated that there had been incidents of reported child abuse and that Child Protective Services had attempted to visit the Hart family a few days before they left their home in Washington.
He noted the Yukon had traveled some 23 metres along an unpaved roadside pullout before running off the cliff, leaving behind no skid or brake marks, indicating the vehicle may have been driven off the cliff intentionally.
Beginning in 2008, Sarah and Jennifer Hart faced repeated child abuse allegations from teachers and neighbors as they moved from Minnesota to OR to Washington with their six adopted children.
The 100-foot drop killed the women, both 39, and their children Markis Hart, 19; Jeremiah Hart, 14; and Abigail Hart, 14. Devonte Hart had made headlines years before the crash when a picture of him hugging a police officer during police-brutality protests went viral. The crash happened just days after authorities in Washington state opened an investigation following allegations the children were being neglected. The friend was unable to reach her after that.
The moms, married couple Jennifer and Sara Hart, who died in the crash, had six adopted children.