Elite rock climber Tommy Caldwell was near breaking point.
The 21-year-old and his three friends were living a nightmare in the unforgiving Kyrgyzstan mountains after being captured by armed rebels.
With dwindling supplies, they had endured brutal marches over perilous hillsides, relentless gunfire and the traumatic execution of a fellow captive in front of them.
By the sixth day, they were feeling desperate. Their kidnappers showed no sign of releasing them and the climbers increasingly feared they would not make it out alive.
Suddenly, an opportunity for escape presented itself and Caldwell made a split-second decision that would change his life forever.
Seizing the chance to save himself and his companions, he grabbed the gun strap of their lone captor and hurled him off a cliff.
Stunned, he watched as the rebel’s body plummeted 30 feet, ricocheted off a ledge and disappeared into the dark abyss below.
In that haunting moment, the young climber truly believed he had killed a man - something he never thought possible.
Fast forward to the present day and Caldwell has now revealed how he is surprised the harrowing experience in 2000 has not left him more traumatized.
Pictured: Tommy Caldwell, Beth Rodden, Jason Smith, and John Dickey speaking to reporters aboard a helicopter in Kyrgyzstan after their escape
Pictured: The Pamir-Alai mountain range of Kyrgyzstan where Caldwell and his friends were captured
Caldwell was held hostage by members of the Islamic Movement of Uzbekistan during a 2000 trip to Kyrgyzstan
Caldwell is currently promoting his National Geographic documentary, The Devil's Climb, which chronicles his latest adventure with Alex Honnold of Free Solo fame.
The duo were seeking to break a world record by climbing the five massive, icy granite towers of Alaska's Devil's Thumb in one day - after a grueling 2,600 mile month-long bike ride across North America.
The mountain is notoriously dangerous, known for avalanches and brutal storms, with few successful summits in history.
Caldwell viewed the journey as a test of human endurance, embracing the challenge of relying solely on their own strength to reach such a remote location.
During the film he spoke about how past adversity and personal setbacks had helped him take on the new high-stakes adventure after suffering an Achilles injury that had required multiple surgeries.
He compared training resilience to building muscle, explaining that it requires consistent practice.
'You just expose yourself to minorly traumatizing things at a slightly increased dosage over time,' he told Business Insider. 'That gets you used to it'.
Caldwell also recalled making the difficult decision to push his captor off a cliff which he believed 'psychologically added power' and bolstered his belief in himself.
The ordeal had occurred in 2000 when he and his then girlfriend Beth Rodden had embarked on an expedition to Kyrgyzstan, a mountainous region bordering China.
While camped on a cliffside early one morning, gunfire shattered the dawn, and the climbers found themselves taken hostage by armed rebels from the Islamic Movement of Uzbekistan, who were at war with the Kyrgyz government.
For six days, Rodden, Caldwell, and their companions, John Dickey and Jason Smith, were forced to cope with both the physical hardships of their captivity and the psychological toll of being held by violent militants.
Pictured: Tommy Caldwell with his wife, Rebecca Pietsch, and their son and daughter
Seizing the chance to save himself and his companions, Caldwell grabbed the gun strap of their lone captor and hurled the man 20 feet off the cliff
Recalling the moment of their capture, Caldwell, then 21, told National Geographic in a 2003 interview that the group had been awakened by three gunshots very close to where they were sleeping.
Caldwell said: 'We were looking through our camera lenses, and we could see them waving to us and they kept shooting at us. And they were getting pretty close.'
John volunteered to investigate and quickly radioed back, urging the group to come down from the cliffs where three rebels were waiting at the base of the mountain.
Rodden recalled the men had full beards, were dressed in army fatigues and armed with rifles, grenades, handguns, and knives.
Though the rebels appeared friendly at first, the climbers understood that their captors were dangerous and that compliance was the only option for survival.
The rebels forced the climbers to lead them to their main camp, where they looted their belongings and ate their food.
At the camp, they encountered another prisoner, a Kyrgyz soldier, who communicated to them, through gestures, that the rebels had killed many soldiers and had no intention of releasing their captives.
As they moved through the wilderness, they had to evade government helicopters searching for the rebels.
Caldwell recalled: 'When a helicopter would fly over, they would point their guns at us and tell us to hide in the bushes. And at one point, in the bushes one of the rebels pointed the gun directly at John's head and said, 'If you move, you're dead.''
The situation took a darker turn when a firefight erupted between the rebels and Kyrgyz soldiers. Hiding in the bushes as bullets flew past, the group witnessed the rebels execute the captured soldier.
'We were just hiding in bushes, and there was bullets going through the bushes, so our captors told us to run up to this rock. But first they told the Kyrgyz soldier that was with us to run up there and after he got behind the rock, we heard two pops and they had executed him,' said Caldwell.
With food running low and their situation growing more desperate, the climbers resorted to rationing power bars. Caldwell and Jason frequently discussed escape plans, but Rodden feared it would result in certain death.
The opportunity came unexpectedly when three of the rebels moved on, leaving just one man behind to guard the climbers as they ascended a steep ridge.
As they neared the top, Caldwell seized the chance. 'I ran up behind him, grabbed him by his gun strap, and pulled him over the edge,' he said.
'We were probably about 2,000 feet (610 meters) above the river, but it's a cliff that is pretty sheer. We saw him fall 20 feet (6 meters), bounce off this ledge, and then fall basically into the black abyss below.'
Caldwell, overwhelmed by what he had just done, broke down.
'I totally panicked. I broke down. I couldn't believe I'd just done that, because it's something that I never morally thought I could do and I never wanted to do,' he said.
The climbers fled and eventually stumbled into a Kyrgyz Army camp hours later.
To Caldwell's surprise, the man he believed he had killed survived the fall. However, the rebel was later captured by Kyrgyz soldiers and sentenced to death.
'I totally panicked. I broke down. I couldn't believe I'd just done that, because it's something that I never morally thought I could do and I never wanted to do,' he said
When discussing why the traumatic kidnapping experience has not impacted him more in his National Geographic documentary, he came up with one possible theory from reading a book by psychotherapist Peter Levine called 'Waking the Tiger'.
The book suggests that people who cope best with trauma are those who find ways to regain control in dangerous situations, Business Insider reported.
'In Kyrgyzstan, I was the one who made the hard decision,' he said. 'I was the one that decided to get us out of there by pushing this guy off a cliff.'
'Now I know if I'm in a hard situation, I can do the right things to get out of it.'
After surviving the kidnapping, a freak accident led to the amputation of his left index finger during a home renovation.
Doctors predicted this would end his climbing career, but Caldwell refused to accept that fate, instead using it as motivation to surpass expectations - including free-climbing the 3,000 foot vertical face of El Capitan in Yosemite National Park, which later became a film called The Dawn Wall.