Last Updated 7:57 a.m. ET
Released from an Iranian prison after 410 days of solitary confinement, Sarah Shourd says she cannot feel the joy of freedom as long as her two fellow Americans remain imprisoned.
"I thought this would be the end, and at this point I don't know when the end is going to come," Shourd said on CBS' "The Early Show." "So now I'm in this position the families have been in all along, of anxiety and uncertainty and really no guarantees.
"Of course, we have hope, but we don't know when this is going to end."
Shourd, her boyfriend Shane Bauer and their friend Josh Fattal were detained by Iranian troops in July 2009 while hiking near the Iran-Iraq border. Iran said the Americans had crossed into that country illegally, and they faced charges of espionage.
Shourd was released on September 14 after negotiations mediated by Oman.
She has protested her innocence and that of her friends, of whom she has heard nothing since she was released.
"As soon as I left the prison walls behind me, there's absolutely no communication, and I have no way of knowing if they're okay or what's going on with them, you know, if there's been changes in their conditions now that I'm not there any longer," she told "Early Show" anchor Maggie Rodriguez.
Shourd described her experience in prison on CBS and in an interview with the Associated Press.
Shourd was kept in solitary confinement at the notorious Evin Prison in Tehran, in a cell she said was 5 feet by 10. For the first few months, she was granted no time outside, before being allowed to spend a half-hour or hours in a courtyard with her friends.
"It slowly increased with begging and pleading and, you know, a lot of tears," Shourd told Rodriguez. "But I would, you know, anticipate and center my whole day around that time, it was my only human contact. So when the hour drew near and I never exactly when I would be taken out but I would start pacing around the room and wringing my hands and often just crying full of anxiety.
"And when I saw them, Shane and Josh, Just incredibly compassionate, supportive young men, we would sit around in a circle and hold hands. Every time I felt I was slipping away they would bring me back.
"Shane and Josh were my lifeline," Shourd said.
When asked if the guards in the prison were kind to her, Shord replied, "It's a mixed bag. Some are really compassionate. I mean, it's a difficult job to have, to have to watch people suffering."
Shourd noted that the pain of prisoners in invisible to the outside world. "We can't see Shane and Josh right now, even though they're cramped in a little cell. Their cell is the same size as mine was, but there's two of them in there, so really with their beds taking up half the room they exercise side by side on a space the size of a towel, and they have no idea when they are going to get out. They've committed no crime. They don't deserve to be there.
"I want to make their pain more visible because when I was there my pain was invisible. And, you know, even the guards could just slam the door and walk away, no matter how much I cried and or at times I screamed, you know?"
She is hopeful that she will be reunited with her friends, including her fiancé Shane, and that she can have her wedding soon.
"Yeah, of course I'm hopeful. I mean, you know, hope is what sustains you," she said. "We know this is going to end. There's too many people and governments around the world that want this to end and I believe there can be a resolution that both sides are a satisfied with. I believe it's better for everyone to end this."
Shourd recalled to the Associated Press how the three made a vow while blindfolded in a prison van shortly after their capture: If they were separated, they would go on hunger strike until they were reunited.
Shourd starved herself for four days, lying alone in her cell and growing weaker. In prison, she kept reviewing her last day of freedom. What could they have done differently? What if, when they asked a tea vendor near a waterfall for advice on a hiking path, they had gone another way?
On the fourth day, the hikers were reunited for five minutes. Shourd began eating again, but their captivity was just beginning.
Alone in her cell, Shourd began going over multiplication tables in her head. It was the only way she could keep out thoughts of her mother. Of whether she knew where her daughter was. Of how worried she must be. Of whether they would see each other again.
If she thought of her mother, she began to fall apart, Shourd recalled.
"I just had to be sure that I was strong when I went into the interrogation room because I wanted to make sure that I didn't, that they didn't manipulate me into saying anything that I didn't want to say," she said.
She wondered whether she'd be hurt. If suddenly the door might open and she'd be dragged away.
Instead, a few times a day, a female guard would come bearing layers of extra clothing and a blindfold, so when Shourd arrived at the interrogation room she couldn't see the faces of her questioners.
She was amazed at their "good cop, bad cop" approach, just like on TV shows back in the U.S.
They had her write down what felt like every detail of her life, from her childhood in Los Angeles to her time living with Bauer in Syria, where she taught English and Bauer, a native of Onamia, Minn., was a freelance journalist. Fattal, who grew up in Pennsylvania, had come to the Middle East to visit them.
Over two months, she wrote hundreds of pages, she said. When she would finish writing an answer to a question, an interrogator would tell her "this is not good enough" and tear up her words. She would write again, and again hear the pages tear.
"I would just write it the same every time," she said.
They questioned her about her e-mails and about her Skype contacts, looking for any indication she had intended to come to Iran.
Should says she had been missing the green mountains of the U.S. after a year in Syria. She and Bauer had heard from friends that the lush lands of northern Iraq had been largely untouched by the war. So they and Fattal traveled to Ahmed Awa waterfall, where they found hundreds of Kurdish families eating at restaurants and camping.
The first indication they were near the Iran border was three hours into their hike when they met Iranian officials on a trail leading from the waterfall. By then, it was too late.
Shourd tried to resist her imprisonment at first. She constantly yelled, cried or begged her captors for a phone call. She was confined to her 10-foot-by-5-foot cell. At night, the bit of sunlight from the window would dim, but the lights stayed on.
Eventually, the interrogations ended. The two men were moved into a cell together. The three Americans were allowed to see each other, at first for 30 minutes each day, then for an hour, then for two.
The trio had local TV, including 15 minutes of English-language news every day. They received a bundle of letters from their parents and siblings about once a month. And they had books in English. Shourd read the Quran, using her basic Arabic to communicate haltingly with some Farsi-speaking guards about religion.
Shourd would spend all day saving up details to tell the other two. At first, the three went over what they called "reruns" - reviewing every memory of their lives in tremendous detail. When those ran out, they started to dream of the future and what they would do on the outside.
Some plans were bigger than others.
On one evening, Bauer asked Fattal to stay in their cell during their allotted time outdoors, so that the couple could have a moment alone.
The two sat on a rough wool mat, cockroaches skittering around them and dust filling the air. They held hands, and Bauer asked her to marry him. He made them engagement rings from two thin pieces of string.
"It's not what every person thinks of as romantic, but it was romantic for me," Shourd said.
Shourd also recalled the celebration of her 32nd birthday last month. Somehow Bauer and Fattal had persuaded a guard to bring her a cake.
And now, she is back on the outside, appearing on "The Oprah Winfrey Show," preparing for a tour of TV studios, a bit of string tied around her finger.
She feels some guilt, she said, but she pushes that aside. She learned in prison how to ignore negative emotions.
She thinks of the men, of the strong, supportive faces they put on when they learned only she would leave. She still doesn't know who paid her $500,000 bail, though she said an Omani official told her of an Iranian citizen who attempted to mortgage his home to pay it.
Iranian President Mahmoud Ahmadinejad has told the AP that he hopes Bauer and Fattal would be able to provide evidence that "they had no ill intention in crossing the border" so that they can be released. Iran has issued espionage-related indictments against the three of them, which could bring trials for the two men and proceedings in absentia for Shourd, although she says she hasn't ruled out returning to face trial.
She wants the world to see Bauer and Fattal, who are passing long days in a cramped space not much larger than a towel.
Shourd said they exercised to stay sane. There were days she would force herself to run or do jumping jacks despite the tears streaming down her face.
The men got even more inventive. They would lift their beds. They would stockpile water bottles, fill them with water, pile them into bags and lift them. They were intent on staying strong.
Part of her wishes she were still with them. Out here she can't protect them. She doesn't know that the books are still available or whether the guards are still being kind.
"The only thing that gives my freedom meaning is that I have this work to do, because honestly if I felt like there was nothing to do out here, if I wasn't needed in so many ways, I would have rather stayed with them," she said.
But out here, she can be their voice. She can do her best to make sure the world doesn't forget. She will be tireless, she said.
And until they're at her side, "my life will not resume."
© 2010 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.