Sunday evening, 17-year-old Carter Christensen posted a selfie on Instagram, the caption "Free climbed 1st flatiron" written below a photo that captured his smiling face and, over his shoulder, the view from atop one of Boulder's iconic landmarks.
It was the last image Christensen would upload to the popular photo-sharing app, as he fell to his death just an hour later — the first accidental climbing fatality on the Flatirons in nine years.
"I couldn't believe it," said Michael Kelly, who learned the news upon arriving at Chautauqua Park that night as he searched for his friend. "The first thing I thought of was that picture. I just pulled it up on my phone and I just looked at it."
It's a photo that will be viewed through many teary eyes this week, as family and friends mourn the death of Christensen, an aspiring Navy SEAL who spent a good portion of his childhood and teenage years in Longmont.
Though Christensen and his family had been living in Maple Grove, Minn., for the past few years, he came back to Colorado every summer.
"His heart was always in Colorado," said his friend Lexi Quach, who went to high school with Christensen in Minnesota. "He always loved going there. He would tell me how excited he was for summer to go and visit."
And while they're grieving, Christensen's friends and family have taken some comfort in knowing the teen was in the outdoors one last time.
"It's a terrible way for such a young man to go, but I know that if there is any way he wanted to go, it would have been like this," Kelly said. "He died in a place he loved, doing what he loved."
Christensen's family even requested the Boulder County Coroner's Office release the photo he took during that last climb when officials publicly identified him on Wednesday.
"Carter was a lover of the outdoors and an adventurous spirit and was experiencing joy in summiting the First Flatiron in Chautauqua Park," the family said in a prepared statement. "Carter came to Colorado to be outdoors in a place that he loves.
"Carter will be loved and missed by all of his family and friends."
'We went to Chautauqua all the time'
Boulder County sheriff's officials said Christensen was free-soloing — climbing alone, without the use of ropes or gear — on the First Flatiron on Sunday evening when he fell 100 feet or more, suffering "massive traumatic injuries."
Rescuers were unable to revive him, and he was declared dead at the scene.
Christensen had climbing experience, and had been up the Flatirons — though Kelly said he had never reached the top of the First Flatiron before Sunday.
"We went to Chautauqua all the time," Kelly said. "He's gone up alone before too. He just loves it."
Kelly said he saw Christensen the day before his death, and said Christensen didn't mention anything about a climb.
"The only way we knew he was up there was because of the photo," Kelly said of the Instagram posting. "I just think he woke up in the morning and was needing something to do."
But Kelly said the friend Christensen was staying with called Sunday night to say he hadn't heard from Christensen all day. One friend called police while Kelly headed from Berthoud to Boulder.
"I saw the picture so I knew where he had been, so I got a pack and I was hauling ass down the Diagonal (Highway), trying to get to Chautauqua," Kelly said. "But when I got there, there was a police officer already waiting.
"My friend had already talked to him, and he came up and all he could say was, 'He's dead.'"
'He was so driven'
Kelly said Christensen originally was from Minnesota, but moved to Longmont and lived there from fourth grade until high school. While he wound up moving back to Minnesota, he still thought of himself as a Coloradan.
"He was definitely a native," Kelly said. "I don't know how to explain it. He knew the mountains better than anyone. He loved those mountains."
Quach met Christensen when he moved to Minnesota and started attending the same school as her, Maple Grove Senior High, in a Minneapolis suburb. While she said he initially was quiet, they became good friends.
"We would just have talks," Quach said. "He was just very giving and wanted to help people. He was a good friend, and he listened."
Quach said even in Minnesota, Christensen spent most of his time outdoors.
"He was always in his Jeep riding around with his dog," Quach said. "He would send us videos of him mudding. He just liked being in nature."
Christensen's other passion was the military, and his goal while growing up was to become a member of the Navy's elite SEAL division.
"I know he was really looking forward to going into the Navy and fighting for his country," Quach said.
"That's all he wanted to do," Kelly added. "With the determination he had, the personality, the commitment, no one doubted he could have done it."
Christensen was planning on taking a year off before enlisting.
Kelly said Christensen was determined, brave and a leader — traits that would have served him well in the military, but also in life.
"Whenever we went out camping or hiking, he was always leading the pack," Kelly said. "He was one of a kind. You meet so many fake people, but he was the most real person you could meet. He was so driven by what he wanted to do. When he set his mind to something, he achieved it.
"There was no one else more outdoorsy, more adventurous, more outgoing than him. He could have done whatever he wanted to do in life."