(NewsNation) — The sister of a 19-year-old Oklahoma teen found dead along a highway believes people are withholding information about what occurred at a party in the hours before his death last year.

Madison Rawlings told “NewsNation Prime” in a Saturday interview, that she thinks “something happened at the party that (her brother Noah Presgrove) was attending the night before. And I just think that people know and they need to speak up.”

Presgrove’s body was discovered wearing nothing but shoes, along a rural stretch of US 81 in Jefferson County, Oklahoma, on Labor Day in 2023. His family says he was last seen alive at a party he attended with a group of friends.

The teen had a caved-in skull, road rash on his hip, a gravel rash on his shoulder, multiple bruises and scattered teeth.

While the Oklahoma Highway Patrol said it is not investigating Presgrove’s death as a murder, Rawlings issued a plea to anyone present at the party who may have witnessed something or has photos or videos.

“I just hope that they can find it in their hearts to just do the right thing,” she said. “And if you’re doing the right thing, then that’s all that we can ask of you.”

Presgrove had spent the evening drinking at the house party with friends. At some point, he was involved in an ATV accident, got into a fight with his girlfriend and then left, never to be seen alive again.

Though Rawlings said she doesn’t want to accuse anyone, she believes there are people withholding information about what transpired at the gathering. “I just want to know … how he died,” she said.