ARUN RATH, HOST:
We've heard a lot about how the group that calls itself the Islamic State, or ISIS, has mastered social media like Twitter. Ellie Hall, a reporter for BuzzFeed News, has been tracking the tweets of female ISIS recruits. Recently, a woman with the handle Umm Jihad caught her attention.
ELLIE HALL: She said that someone should kill the president. She called President Obama a treacherous tyrant. She advocated - she said, why don't you go rent a car and drive over everybody at a Patriots' Day Parade?
RATH: The full ID on twitter was Umm Jihad al Amrika - the mother of jihad from America. And Hall was not alone in following her.
HALL: She was being supported. She was making friends. People were retweeting her. She had thousands of followers. And that's how ISIS uses Twitter to recruit women. They create this online sisterhood where you feel loved.
RATH: But before Umm Jihad was tweeting about killing Americans, before she left America, she tweeted about normal, everyday stuff. Her name is Hoda. She tweeted about her home, Alabama, and about her siblings. So Ellie Hall was able to track down Hoda's family and meet her father for an interview.
HALL: It was heartbreaking. It was absolutely heartbreaking to talk with Hoda's father. He cried during the interview. I got teary. It's - the heartbreak this family is experiencing - it knows no bounds.
RATH: Her father's name is Mohammed, but the family didn't want their last name used; they're worried for their safety. Hall says Mohammed had no idea his daughter was radicalizing. The family in Alabama is culturally conservative - restrictions on kids going out, interactions with opposite sex, that kind of thing - but certainly not radical and not unusual. Mohammed didn't let Hoda have a mobile phone until she graduated high school in 2013, and even then he kept tabs.
HALL: They were afraid that she might be talking to boys. She was always on her phone. So her father would routinely inspect her phone to see what she was doing. And he said he was impressed because it was only these apps about the Quran - memorizing the Quran. And that's how she spent her free time they thought.
RATH: Mohammed thought his daughter was just becoming more devout, and he was proud. He didn't realize she was radicalizing - fast. Hoda started college at the University of Alabama, Birmingham, but she still would routinely ask her dad's permission to go out. Last November, she made a request.
HALL: She told her parents that she had to go to Atlanta for a school trip, and they said no, absolutely not. And then she said, you know, my grades will be affected.
RATH: Mohammed relented. The day came, Hoda left for campus with just a purse and a school bag, like every other day. Then, that evening, Hoda called her sister with a bogus story about getting on the wrong bus. A day passed with no word from her.
HALL: Around this time, when they were beginning to think something was wrong, Hoda had landed in Turkey. And she had purchased a new cell phone, and she used this to send a message to her sister. She said, you know, I am here. I am in Turkey. I'm going to cross the border. This is what I'm doing.
RATH: Mohammed was on a work trip in Washington, D.C., and had no idea until he picked up a phone call from his other daughter.
HALL: And she was screaming, Hoda lied to us. She's in Turkey. She's going to join ISIS. She lied to us.
RATH: Mohammed was bewildered and devastated.
HALL: He said, in the beginning, he was proud. He was proud to see Hoda, you know, memorizing one of the longest pieces of scripture in the Quran, Sourate Al-Kahf. He said, you know, I thought she was a good Muslim, a true Muslim. He has no idea what happened.
RATH: Mohammed had never seen the tweets that Hoda had sent as Umm Jihad.
HALL: He started crying when he read them. I remember, he looked up and said, it looks like she's gone. It looks like we lost her.
RATH: After Ellie Hall located her family, Hoda agreed to talk over the instant messaging app Kik. Hall told Hoda how distraught her family was.
HALL: I was really unnerved by how Hoda dismissed all of this - her parents' pain.
RATH: Hoda's family was still holding out hope she might come home, but that was quickly dashed.
HALL: She told me flat out she's not coming home, has no desire to. But seeing Mohammed realize that the daughter he raised has become someone completely different was heartbreaking.
RATH: Less than a month after she arrived in Syria, Hoda married a 23-year-old ISIS fighter, another runaway from Australia. She told Hall that the marriage wasn't forced, but she's already a widow. According to Hoda, her husband was killed in an airstrike 87 days after they married. Hoda says she's now in a mourning period and living in a home for widows in Syria. Transcript provided by NPR, Copyright NPR.