We arrived at the frozen river separating China and North Korea at 5 o’clock on the morning of March 17. The air was crisp and still, and there was no one else in sight. As the sun appeared over the horizon, our guide stepped onto the ice. We followed him.

We had traveled to the area to document a grim story of human trafficking for Current TV. During the previous week, we had met and interviewed several North Korean defectors -- women who had fled poverty and repression in their homeland, only to find themselves living in a bleak limbo in China. Some had, out of desperation, found work in the online sex industry; others had been forced into arranged marriages.

Now our guide, a Korean Chinese man who often worked for foreign journalists, had brought us to the Tumen River to document a well-used trafficking route and chronicle how the smuggling operations worked.

There were no signs marking the international border, no fences, no barbed wire. But we knew our guide was taking us closer to the North Korean side of the river. As he walked, he began making deep, low hooting sounds, which we assumed was his way of making contact with North Korean border guards he knew. The previous night, he had called his associates in North Korea on a black cellphone he kept for that purpose, trying to arrange an interview for us. He was unsuccessful, but he could, he assured us, show us the no-man’s land along the river, where smugglers pay off guards to move human traffic from one country to another.

When we set out, we had no intention of leaving China, but when our guide beckoned for us to follow him beyond the middle of the river, we did, eventually arriving at the riverbank on the North Korean side. He pointed out a small village in the distance where he told us that North Koreans waited in safe houses to be smuggled into China via a well-established network that has escorted tens of thousands across the porous border.

Feeling nervous about where we were, we quickly turned back toward China. Midway across the ice, we heard yelling. We looked back and saw two North Korean soldiers with rifles running toward us. Instinctively, we ran.

We were firmly back inside China when the soldiers apprehended us. Producer Mitch Koss and our guide were both able to outrun the border guards. We were not. We tried with all our might to cling to bushes, ground, anything that would keep us on Chinese soil, but we were no match for the determined soldiers. They violently dragged us back across the ice to North Korea and marched us to a nearby army base, where we were detained.

Over the next 140 days, we were moved to Pyongyang, isolated from one another, repeatedly interrogated and eventually put on trial and sentenced to 12 years of hard labor.

During our time in captivity, and in the weeks since we returned, there has been speculation about what we were doing in that part of the world and about what happened on the morning of the 17th. After arriving home, we were disoriented, overwhelmed and not ready to talk about the experience. There are things that are still too painful to revisit, but we do want to explain what took us to northeastern China and the circumstances of our arrest.

Our motivations for covering this story were many. First and foremost, we believe that journalists have a responsibility to shine light in dark places, to give voice to those who are too often silenced and ignored. One of us, Euna, is a devout Christian whose faith infused her interest in the story. The other, Laura, has reported on the exploitation of women around the world for years. We wanted to raise awareness about the harsh reality facing these North Korean defectors who, because of their illegal status in China, live in terror of being sent back to their homeland.

In researching the story, we sought help from several activists and missionaries who operate in the region. Our main contact was the Seoul-based Rev. Chun Ki-won, a well-known figure in the world of North Korean defectors. Chun and his network have helped smuggle hundreds of North Koreans out of China and into countries -- including the U.S. -- where they can start new lives. He introduced us to our guide and gave us a cellphone to use in China, telephone numbers to reach his associates and specific instructions on how to contact them. We carefully followed his directions so as to not endanger anyone in this underground world.

Because these defectors live in fear of being repatriated to North Korea, we took extreme caution to ensure that the people we interviewed and their locations were not identifiable. We met with defectors away from their actual places of work or residence. We avoided filming the faces of defectors so as not to reveal their identities. The exception was one woman who allowed us to film her profile.

Most of the North Koreans we spoke with said they were fleeing poverty and food shortages. One girl in her early 20s said she had been told she could find work in the computer industry in China. After being smuggled across the Tumen River, she found herself working with computers, but not in the way she had expected. She became one of a growing number of North Korean women who are being used as Internet sex workers, undressing for online clients on streaming video. Some defectors appeared more nervous about being interviewed than others. But they all agreed that their lives in China, while stark, were better than what they had left behind in North Korea.

We also visited a foster home run by a pastor who worked for Chun. The home housed six children born to North Korean women who were forced into marriage in China. The mothers had either been repatriated to North Korea or had abandoned their families. Because the children have Chinese fathers, it is unlikely they will be deported to North Korea. The foster home provides them with decent conditions, an education and hope for a better life.

In the days before our capture, our guide had seemed cautious and responsible; he was as concerned as we were about protecting our interview subjects and not taking unnecessary risks. That is in part why we made the decision to follow him across the river.

We didn’t spend more than a minute on North Korean soil before turning back, but it is a minute we deeply regret. To this day, we still don’t know if we were lured into a trap. In retrospect, the guide behaved oddly, changing our starting point on the river at the last moment and donning a Chinese police overcoat for the crossing, measures we assumed were security precautions. But it was ultimately our decision to follow him, and we continue to pay for that decision today with dark memories of our captivity.

After we were detained, the two of us made every effort to limit the repercussions of our arrest. In the early days of our confinement, before we were taken to Pyongyang, we were left for a very brief time with our belongings. With guards right outside the room, we furtively destroyed evidence in our possession by swallowing notes and damaging videotapes. During rigorous, daily interrogation sessions, we took care to protect our sources and interview subjects. We were also extremely careful not to reveal the names of our Chinese and Korean contacts, including Chun. People had put their lives at risk by sharing their stories, and we were determined to do everything in our power to safeguard them.

Our families and colleagues back home maintained total silence about our work for two full months, both to minimize the potential impact on sensitive underground work in China and to protect us. We were surprised to learn that Chun spoke with reporters publicly in the immediate aftermath of our arrest. Among other things, Chun claimed that he had warned us not to go to the river. In fact, he was well aware of our plans because he had been communicating with us throughout our time in China, and he never suggested we shouldn’t go. Chun’s public statements prompted members of our families to speak directly with him in Korean, pleading with him to refrain from any further comment that might jeopardize our situation and those of relief organizations working along the border.

After spending nearly five months in captivity, we were relieved to be granted amnesty by the North Korean government. We continue to cope with tremendous mental and emotional anguish, but we feel incredibly fortunate to be free and reunited with our families. We are forever indebted to the United States government, particularly the State Department, to President Obama and Secretary of State Hillary Rodham Clinton, to former Vice President Al Gore and our colleagues at Current TV, to Swedish Ambassador Mats Foyer, and to former President Clinton and his team for taking on this private humanitarian mission.

We can’t adequately express the emotions surrounding our release. One moment, we were preparing to be sent to a labor camp, fearing that we would disappear and never be heard from again; the next we were escorted into a room with President Clinton, who greeted us and told us we were going home. We are grateful to the many journalists who kept our story alive. We are humbled by the tens of thousands of people who supported us, prayed for us and fought for our release.

At the same time, though, we do not want our story to overshadow the critical plight of these desperate defectors.

Since our release, we have become aware that the situation along the China-North Korea border has become even more challenging for aid groups and that many defectors are going deeper underground. We regret if any of our actions, including the high-profile nature of our confinement, has led to increased scrutiny of activists and North Koreans living along the border. The activists’ work is inspiring, courageous and crucial.

Many people have asked about our strength to endure such hardships and uncertainty. But our experiences pale when compared with the hardship facing so many people living in North Korea or as illegal immigrants in China.

The outcome of our three-day trial was never in doubt. In the end, we were convicted and sentenced to two years for trespassing and 10 years for “hostile acts.” What did we do that was hostile? We tried to tell the story of repression and desperation in North Korea. It’s not surprising, given the North Korean government’s desire to silence any form of dissent, that the more extreme portion of the sentence was issued not for trespassing but for our work as journalists. Totalitarian regimes the world over are terrified of exposure.

We know that people would like to hear more about our experience in captivity. But what we have shared here is all we are prepared to talk about -- the psychological wounds of imprisonment are slow to heal. Instead, we would rather redirect this interest to the story we went to report on, a story about despairing North Korean defectors who flee to China only to find themselves living a different kind of horror. We hope that now, more than ever, the plight of these people and of the aid groups helping them are not forgotten.

Laura Ling is a correspondent for Current TV and vice president of its Vanguard Journalism unit. Euna Lee is a producer and editor for Current’s Vanguard series. To see more of their work, go to current.com.