A 16-Year-Old Girl Disappeared on a 1976 Field Trip and Hasn't Been Found

The skies were dreary the morning of October 8, 1976, when Hope Gibson dropped off her daughter, Trenny Gibson, at Bearden High School in Knoxville, Tenn.

Despite the rainy weather, the 16-year-old was still scheduled to embark on a field trip to the Great Smoky Mountains National Park with 40 fellow students from her horticulture class, and their lone teacher, Deadrick Wayne Dunlap.

“She said she would call me as soon as they got back, and she kissed me ‘bye,’” Hope tells A&E Crime + Investigation.

Trenny told her mom she expected to be back at school around 5:30 p.m. and that she’d give her a call when they returned.

Hope, now 87, watched as her daughter walked into the school.

“The last thing I saw her do was put her comb in her back pocket,” she recalls.

At 8:30 p.m., the Gibson family’s phone rang. It was school guidance counselor Talmage Hooker on the other end of the line.

“I can still hear it today,” Hope remembers. “He said, ‘Trenny’s lost in the mountains.’ Just like that.”

Trenny never made it back home, and her disappearance shattered the Gibson family. Her parents divorced, and her father and two of her three siblings have since died.

Hope continues to cling to the possibility that Trenny is still alive somewhere.

“For 50 years,” she admits, “I've been searching for that sweet little face.”

Trenny was a middle child, wedged between her older brother, Robert Jr., and younger siblings, Tina and Miracle.

“She loved her family more than anything,” Hope says. “I can’t even express to you what a joy she was.”

By her mother’s account, Trenny was a homebody who loved to read, shop and sing in her junior church choir. She worked part time at a diner and aspired to attend the University of Tennessee, where she planned to study landscape architecture.

“Trenny was just a very different individual,” Hope says. “She was geared more toward learning and enjoyed doing things that would give her more knowledge.”

When Hope and Trenny first pulled up to Bearden High School that morning, the teen ran inside to confirm the status of the field trip due to the inclement weather.

Soon after, Trenny came back out to the car to let her mom know the class still planned to venture to the Great Smoky Mountains National Park despite the rain.

As she approached the vehicle, Hope noticed her daughter was accompanied by classmate Robert Simpson Jr., who lent Trenny his brown plaid Chief Petty Officer coat so that she wouldn’t have to run back home for a jacket of her own.

“It came almost to her knees, as small as she was, and as large as he was,” Hope recalls. “It swallowed her whole.”

After saying their goodbyes, Trenny and Simpson disappeared back into the school, Hope says.

They boarded the bus with their horticulture classmates around 9 a.m.

According to Michael Bouchard, a 40-year police veteran and the author of TRENNY: The Disappearance of Trenny Lynn Gibson, Simpson reportedly informed his peers that he was keeping an eye on Trenny that day.

“He basically stated to everyone that he was” acting as her “chaperone because her [older] brother had asked him to watch over her,” Bouchard tells A&E Crime + Investigation.

The students arrived at the Clingmans Dome parking lot three hours later. At around 12:30 p.m., they made their way to the Andrews Bald Trail to observe the plants and vegetation and were instructed to return to the bus at 3:30 p.m.

At around 1:50 p.m., the students began their trek back to the parking lot.

Trenny subsequently caught up with three other classmates during the journey back. The students decided to take a break, but Trenny—reportedly still dressed in Simpson’s jacket—announced she planned to keep making her way down the Forney Ridge Trail.

She appeared to “be in a hurry to get back,” one witness said.

Shortly after, the group resumed their hike and claimed they saw Trenny walking ahead of them in the distance around 2:50 p.m. One student said they saw Trenny go off the trail and down a hillside teeming with “dense shrubs, scattered rocks and a creek, with no alternate pathways,” Bouchard wrote.

Still, it was assumed Trenny would find her way back to the school bus.

She never did, and a frantic search led by the National Park Service commenced that evening.

At 8:30 p.m., Hope says she was notified by school counselor Hooker that her daughter had vanished in the Great Smoky Mountains.

“I just froze, it was such a shock,” Hope remembers. “It was my baby—the light of my life—and he was telling me she was lost.”

The initial search for Trenny stretched for more than a week, during which scent dogs and helicopters were deployed. Rain and fog hampered their efforts.

No physical evidence or remains were ever recovered.

Although Trenny was described in NPS records as having “very little” outdoor knowledge, her parents firmly believed her disappearance was involuntary and that foul play was involved, according to newspaper clippings.

The Gibsons claimed they also previously received threats about a year before Trenny’s disappearance.

No suspects have ever been tied to the missing teen’s case, but Bouchard alleges Trenny’s fellow classmate, Simpson, who reportedly had a crush on her, was involved.

“This is a homicide,” he says, matter-of-factly. “This isn't a disappearance. She didn’t just walk off.”

Simpson died in 2022.

“Based on the evidence and people's statements, he [Simpson] and Trenny were alone up in Andrews Bald, and he tried to make a romantic advance towards her,” but she rejected him, according to Bouchard.

Three days after Trenny went missing, Simpson was photographed participating in a search party and wearing the same CPO jacket he lent her during the trip, despite witnesses stating they last saw Trenny wearing the coat before she disappeared.

Bouchard also strikes down the claim that Trenny’s older brother, Robert Jr., asked Simpson to look out for his sister on the field trip.

“This claim is misleading, as Bob Jr. had not communicated with Robert Simpson Jr. for over two years,” he wrote, and “prior to Trenny's disappearance, Bob Jr. was engaged in basic military training and was assigned to the battleship U.S.S. Ramsey and had no ability to contact Robert Simpson Jr.”

Bouchard alleges two other pieces of key evidence tie Simpson to the case: Trenny’s beloved Stanley comb, which was later found in his car, and the same comb that Hope says she saw her daughter slip into her back pocket that fateful day; and vertical scratch marks on Simpson’s inner thighs that were reportedly seen by Robert Jr. when Simpson spent the night at the Gibson family’s home following Trenny’s disappearance.

“The fact that the jacket she disappeared with and the comb that was in her pocket ended up being in his vehicle and on him three days later, plus the scratches...” Bouchard’s voice trails off.

Despite these allegations, Simpson was never identified as a suspect or person of interest.

Bouchard alleges the case was mishandled by authorities.

“It’s a shame,” he says.

As a grieving mother, Hope pivots between feelings of despair and optimism.

On one hand, she believes it’s unlikely that she will experience the resolution she’s wished for the past five decades.

“There’s never gonna be any,” she admits. “I lost my family over it. The only peace I have is with my Lord and Savior. He’s the one that’s carried me all this way. There’s no way I’d even be alive today if it weren’t for Him.”

But in a just world, she grasps at the sliver of hope that Trenny is alive and raising a family of her own.

“She’d be married and have a happy home and have children, and have a happy life,” Hope beams. “I've always had that hope that she would be out there somewhere, even though I don't really think so. But I can never give up, and I just keep searching for her face."