Alex, a 23-year-old Sunday school teacher and babysitter, was trembling with excitement the day she told her Twitter followers that she had converted to Islam.

For months, she had been growing closer to a new group of friends online – the most attentive she had ever had – who were teaching her what it meant to be a Muslim. Increasingly, they were telling her about the Islamic State and how the group was building a homeland in Syria and Iraq where the holy could live according to God’s law.

One in particular, Faisal, had become her nearly constant companion, spending hours each day with her on Twitter, Skype and email, painstakingly guiding her through the fundamentals of the faith.

But when she excitedly told him that she had found a mosque just 5 miles from the home she shared with her grandparents in rural Washington state, he suddenly became cold.

The only Muslims she knew were those she had met online, and he encouraged her to keep it that way, arguing that Muslims are persecuted in the United States.

So on his guidance, Alex began leading a double life. She kept teaching at her church, but her truck’s radio was no longer tuned to the Christian hits station. Instead, she hummed along with the Islamic State anthems blasting out of her iPhone, and began daydreaming about what life with the militants might be like.

"I felt like I was betraying God and Christianity," said Alex, who spoke on the condition that she be identified only by a pseudonym she uses online. "But I also felt excited because I had made a lot of new friends."

Even though the Islamic State’s ideology is explicitly at odds with the West, the group is making a relentless effort to recruit Westerners, eager to exploit them for their outsize propaganda value. Through January this year, at least 100 Americans were thought to have traveled to join jihadis in Syria and Iraq, among nearly 4,000 Westerners who had done so.

Alex’s online circle – involving several dozen accounts, some operated by people who directly identified themselves as members of the Islamic State or whom terrorism analysts believe to be directly linked to the group – collectively spent thousands of hours engaging her over more than six months. They sent her money and plied her with gifts of chocolate.

Extensive interviews with Alex and her family, along with a review of the emails, Twitter posts, private messages and Skype chats she exchanged, which they agreed to share with The New York Times on the condition that their real names and hometown not be revealed, offered a glimpse into the intense effort to indoctrinate a young American woman, increasing her sense of isolation from her family and community.

Enticing the Lonely

"My grandparents enjoy living in the middle of nowhere. I enjoy community," Alex said. "It gets lonely here."

She has lived with her grandparents for almost all her life: When she was 11 months old, her mother, struggling with drug addiction, lost custody of her. Her therapist says that fetal alcohol syndrome, which has left Alex with tremors in her hands, has also contributed to a persistent lack of maturity and poor judgment.

That only partly explains what happened to her online, her family says.

After dropping out of college last year, she was earning $300 a month babysitting two days a week and teaching Sunday school for children at her church on weekends. At home, she spent hours streaming movies on Netflix and updating her social media timelines.

Then on Aug. 19, Alex’s phone vibrated with a CNN alert.

James Foley, a journalist she had never heard of, had been beheaded by the Islamic State, a group she knew nothing about.

Riveted by the killing, and struck by a horrified curiosity, she logged on to Twitter to see if she could learn more.

"I was looking for people who agreed with what they were doing, so that I could understand why they were doing it," she said. "It was actually really easy to find them."

She found herself shocked again, this time by the fact that people who openly identified as belonging to the Islamic State took the time to politely answer her questions.

"Once they saw that I was sincere in my curiosity, they were very kind," she said. "They asked questions about my family, about where I was from, about what I wanted to do in life."

One of the first relationships she struck up was with a man who told her he was an Islamic State fighter named Monzer Hamad, stationed near Damascus, the Syrian capital.

Soon they were chatting for hours every day, their interactions giddy, filled with smiley faces and exclamations of "LOL."

"Hole," she wrote at 10:13 a.m. on Oct. 6.

A minute later, she added: "Hello stupid autocorrect."

He replied: "haha how are you?"

"did you think of what i said aboyt islam," he asked, his messages sprinkled with typos.

What happened next tracks closely with the recommendations in a manual written by al-Qaida in Iraq, the group that became the Islamic State, titled "A Course in the Art of Recruiting." A copy was recovered by U.S. forces in Iraq in 2009.

The pamphlet advises spending as much time as possible with prospective recruits, keeping in regular touch. The recruiter should "listen to his conversation carefully" and "share his joys and sadness" in order to draw closer.

In November, a Twitter user called Voyager asked for her email address and told her his name was Faisal Mostafa. He asked for her Skype ID, and soon they began chatting, cameras turned off in keeping with Muslim rules on modesty.

Crossing a Line

By the time Christmas arrived, Alex felt she had crossed a line.

She asked Faisal what it would take to convert.

He explained that all she needed to do was repeat the phrase "There is no God but Allah, and Muhammad is his messenger," with complete belief and commitment, in the presence of two Muslims.

This presented an obstacle for Alex, who still knew no Muslims in person. Faisal argued that she could post her declaration of faith on Twitter, and the first two people who read it would count as her witnesses.

Just after 9 p.m. on Dec. 28 Alex logged on to Twitter.

Faisal acknowledged her declaration right away. So did another online friend, who went by the screen name Hallie Sheikh.

Months later, the Hallie Sheikh Twitter handle came to public attention: That account had briefly interacted with Elton Simpson, the gunman who opened fire on a contest to draw the Prophet Muhammad in Texas, an attack dedicated to the Islamic State.

Applying Pressure

By mid-February, Alex’s virtual community began making more demands. They told her that as a good Muslim she needed to stop following anyone on social media who was a "kuffir," or infidel.

The fact that she continued to follow a handful of her Christian friends proved to be unacceptable. On Feb. 16, a user on Twitter who openly supported the Islamic State accused Alex of being a spy.

Immediately, people she considered her friends began blocking her.

Faisal interceded on her behalf.

"Your a nice person with a beautiful character," Faisal wrote her. "In many ways ur much better than many so called born muslims."

He added: "getting someone 2 marry is no problem Inshallah."

A few more days passed before he elaborated: "I know someone who will marry you but hes not good looking, 45 bald but nice muslim."

On Feb. 19, Faisal suggested she meet him in Austria so that he could introduce her to her future husband, she said. Alex would need to be accompanied by her "mahram," or male relative. When she asked whether her 11-year-old brother could fulfill that role, Faisal said that would be acceptable.

Two days later, he began asking how and when Alex could get herself and her little brother to Austria.

"Tickets 2 Austria rtn are not that expensive inshallah when (your brother) is ready both come 4 hloiday I’ll buy ur tickets," he messaged on Feb. 21.

Family Intervention

In late March, Alex’s grandmother decided to confront the man she believed was trying to recruit Alex to the Islamic State.

The family gathered in the living room, Alex’s computer propped on the glass coffee table, with a Times reporter and videographer watching. Her grandmother logged in using Alex’s Skype ID.

"You need to know she is very important to us," she wrote. "Why would you EVER think that we would let her leave us under the circumstances you were asking?"

He gave his word he would not contact Alex again.

Alex agreed to hand over the passwords to her Twitter and email accounts.

Waiting until her grandparents were out, Alex logged into Skype, the one account her family had forgotten to shut down.

Faisal wrote her right away, and months later they are still exchanging messages.

"I told her I would not communicate with you," he wrote. "But I lied."