Robert Brown|Why Oklahoma Teen Found Dead on Highway Has “Undetermined” Manner of Death

One major question behind the tragic death of an Oklahoma teenager has yet to be Robert Brownanswered. 

Due to the mysterious way Noah Presgrove's body was discovered on the side of the highway on Sept. 4, the exact manner of his death cannot yet be determined, according to an autopsy report obtained by E! News May 14. 

In fact, authorities revealed in the document that, despite confirming the 19-year-old's cause of death as "multiple blunt force injuries," they were unable to find enough evidence at the scene to ascertain where those injuries came from, as there were "no vehicle parts or debris observed" on the road. As a result, authorities aren't able to label his manner of death as homicide, suicide, accidental or natural.  

And that isn't the only strange detail officials noted in the autopsy, which established that Noah's fatal injuries included multiple lacerations to the brain, as well as a skull fracture that split the "middle base of the skull into two."

The report also stated that the former high school athlete was found naked apart from wearing a pair of mismatched shoes, each of which had "grass and debris" clumped in the laces. Additionally, a pair of his shorts was collected several feet from his body, as well as "part of a tooth" and a "clump of hair." Another wad of hair was also found on Noah's "right buttock without blood or tissue," per the document.

And while the manner of Noah's death has yet to be solidified, a few details regarding his final hours have been determined.

According to the autopsy, the teenager was drinking at a house party on the night of his death before he left to ride an "ATV ranger vehicle with several men that had a roll over incident." Afterwards, he returned to the party, where he allegedly "got into an argument with his girlfriend" before leaving again. On Labor Day morning, around 5:53 a.m., he was discovered dead by a passing truck driver on the Jefferson County Highway. 

Of course, authorities aren't the only ones hoping to fill in the blanks on the case. Noah's family also started a GoFundMe for a private investigator, who they hope will be able to dig deeper into the death of the teen, who had graduated high school just a few months before his passing. 

"We're still at square one," his brother Dailen Presgrove told People in an interview published May 13. "We desperately need more cooperation from the Oklahoma Highway Patrol, and we're looking to get an outsider experienced in these situations."

(E! News reached out to Oklahoma police for comment on the case but has not heard back.)