Noah Presgrove survived the ATV incident before his death, a full autopsy reveals

• Noah Presgrove, 19, was found dead on the side of the road in Terral, Oklahoma on September 4, 2023
• His full autopsy report, obtained by PEOPLE, notes brain swelling and a skull fracture among his many injuries
• “The report answers some questions, but it also raises many more,” Noah’s brother Dailen Presgrove tells PEOPLE

The full autopsy report in the bizarre case of an Oklahoma teenager found dead on the side of the road on September 4, 2023, provides new details about Noah Presgrove’s final hours.

According to the 9-page full autopsy report obtained by PEOPLE, authorities said that “further investigation” revealed that 19-year-old Presgrove was “at a house party drinking” on Sunday, September 3 At one point, he was “driving an ATV Ranger vehicle with several men that resulted in a rollover.”

Presgrove was “still alive after the incident” and then “returned to the party where he got into an argument,” according to the description of the circumstances of his death.

He then “left the house party” and was found dead on Jefferson County Highway at 5:53 a.m. the next morning by a passing truck driver, according to the full autopsy report.

But how he got there remains a mystery.

In the full report, the coroner said Noah died from “multiple blunt force injuries” to his head, neck, torso and extremities and suffered “cerebral swelling” in addition to a two-page list of injuries, including multiple brain tears to the cerebellum and temporal lobes , “basal skull fractures that split the middle skull base in two” and multiple rib fractures.

A molar was broken in half and he also suffered a “laceration on the left surface of the tongue” and four cervical vertebrae fractures.

“It is unknown at this time how the body was found in the street with multiple blunt force injuries,” coroner Leonardo Roquero wrote of his findings, which said the manner of Noah’s death remains “undetermined.” (The report lists Noah by the name Noah Alexander Nichols and his mother’s maiden name.)

Presgrove, who was naked, was found wearing only mismatched shoes: Adidas on the left and Hey Dudes on the right, each with “grass and debris” in the laces, the autopsy report said.

“Three pieces of a white metal chain” and “part of a tooth” were located several feet from his body, along with a pair of his white printed shorts, according to the autopsy report. A strand of hair was in the highway lane and another strand of hair was on his right butt cheek “with no blood or tissue.”

“A drawing of a stick figure person in black ink” was also engraved on the side of his right thigh.

The Oklahoma Department of Public Safety did not immediately respond to PEOPLE’s request for an updated comment on May 13, but earlier this month police confirmed to PEOPLE in a statement that they were continuing to investigate the case but were not treating his death as a homicide examined.

A toxicology report attached to the autopsy report showed that forensic toxicologist Angelica Harper conducted a battery of drug tests for amphetamine, methamphetamine, fentanyl, cocaine, opiates, PCP, barbiturates and benzodiazepines.

None of these drugs were detected in Noah’s system, but alcohol was. Harper further noted that the tests are not intended to detect oxycodone, methadone or clonazepam.

Noah’s brother Dailen Presgrove tells PEOPLE, “The report answers some questions but also raises many more.”

Months after graduating high school and planning to join the military, Noah was described by his family as a four-sport athlete and class clown who was well-liked in his small town. Noah was emancipated at the age of 17 and lived with his grandmother, who raised him at the time of his death.

In the eight months since Noah’s death, rumors about the circumstances leading to Noah’s death have circulated throughout the tight-knit county — and Dailen, whose family started a GoFundMe to cover the costs of hiring a private investigator, tells PEOPLE, that he doesn’t know what to believe.

“We’re still at the beginning,” says Dailen. “We desperately need more cooperation from the Oklahoma Highway Patrol and are looking for an outsider who has experience in these situations.”