Fauna Jackson disappeared during a bathroom break Thursday morning into the deep, rugged wilderness of Grand Teton National Park.

Rangers scoured the area but found no trace of the girl. They expanded their search, setting out across the park’s 310,000 acres — where, between the summits and lakes, live creatures that can kill.

For two days, more than 100 people deployed to look for the 16-year-old from Ohio, there in the park with an environmental group conducting a service project.

Authorities used dogs and ATVs, helicopters and infrared imaging to detect heat sources on the ground. They looked for clues and distributed missing-person posters that described what Jackson was last seen wearing: white hat, tan pants, a long-sleeve green shirt that said “Find Your Park” and “Groundwork USA,” maybe a purple backpack.

But when they finally found Jackson, she didn’t look the same.

Her hair, once long and sandy brown, was now a different cut and color, according to the National Park Service. The teenager had changed clothes.

And as her rescuers approached, she ran not toward them, but away.

They caught up with Jackson on Saturday near the Snake River Outlook, a popular sightseeing spot 3 to 4 miles from where she disappeared. Although she appeared uninjured, Jackson was taken to St. John’s Medical Center for a welfare check, officials said, then placed into the care of the Teton County Sheriff’s Office.

Authorities have yet to explain her odd behavior. Nor has she. Did she leave the park and go somewhere else, have her hair dyed and get a change of clothes and return once more so she could be “found?” Or did she not want to be found at all?

It seemed unlikely.

Activity on her debit card ceased the day Jackson disappeared, stepfather James Bennett told WLWT. The same for her cellphone.

And it seemed unlike her.

A sophomore at Clark Montessori High School in Cincinnati, the teen is known in her community as kind, reliable and a budding young leader, reported the Cincinnati Enquirer.

It was those skills that had brought Jackson to Wyoming in the first place. After spending eight weeks in a youth employment program through the Cincinnati chapter of Groundwork USA, a national civic organization that focuses on green issues, Jackson was selected as one of three teens to make the trip to the Grand Tetons, the newspaper reported.

“She’s very strong-minded, very smart, able to handle all the tasks we had over the course of the summer — trail-building, invasive removal, restoration work,” Alan Edwards, with Groundwork Cincinnati chapter, told ABC affiliate WCPO. “Honestly, one of the best employees we had, and that’s why she got to go.”

The Wyoming trip lasted nine days and included attending a parks-system-sponsored event with outdoor activities, leadership and team-building and fieldwork, Robin Corathers, executive director of the chapter, told the Enquirer. Outdoorsy and an avid gardener, Jackson “worked hard, got along well with the 14 other youths in our summer program, and showed leadership potential,” Corathers told NBC News.

Jackson had been documenting her trip on social media, posting Instagram photos of herself at Old Faithful and atop mountain peaks.

But few if any clues foreshadowing her mysterious behavior were to be found there. On Wednesday, the day before she disappeared, she posted a selfie with two other teens. In the caption, she wrote: “Last day in Wyoming is tomorrow!! I can’t wait to be home and see everyone. Today I’m going to be blazing a trail, pretty siked. I love you all a bunch and can’t wait to see all of you soon!”

Friends and strangers flooded the photo with nearly 150 comments in the days after she disappeared.

“I know her, and I know this is not something that she would do of her own accord,” Chad Vahue, Jackson’s math teacher at Clark Montessori High School, where the girl was a straight-A student and president of the Vegan Club, told NBC affiliate WLWT before Jackson was found.

Her family was just relieved to see her again. “Her condition appears to be good,” Bennett told Fox 19. “We’re just so happy to have our beloved daughter back.”

The details and her physical transformation are still under investigation, officials said.

“This I don’t think anyone saw coming,” Tanner Yess, a Youth Leader with Groundwork Cincinnati, told Fox 19, “but right now we’re just relieved.”