Five years and three husbands later, she says she regrets what she did and urges her to return to the United States.
But after witnessing the devastation of the war, including the deaths of two husbands, Muthana said she had become disillusioned.
"During my years in Syria, I saw and experienced a way of life and the terrible effects of the war that had changed me … See the bloodbath change me My maternity has changed. , children and men that I married dying have changed, "the now 24-year-old wrote.
"See how much a different society can be compared to the beloved America where I was born and in which I grew up." "Where I was and see them? People around me scared me because I realized that I did not want to be part of it … My beliefs were not the same as theirs. "
CNN has not yet been able to talk to him directly.
Once described as shy and reserved by a high school classmate, Muthana was proud of his support for jihad after joining ISIS. At the height of the self-proclaimed caliphate, Muthana posted tweets calling for violence, according to the George Washington University's Program on Extremism.
"Hoda was right in the composition of the English-speaking propagandists," said terrorist researcher Seamus Hughes. "We followed her for several years, she was a key node."
She asked more Americans to surrender to the self-appointed Caliphate and join the struggle with the Islamic State.
"Too many Australians and Britons here, but where are the Americans, wake up, cowards," she published in January 2015.
And under the name of Umm Jihad, she encouraged attacks in the United States. She tweeted this March 2015 exhortation: "Drive out and run all their blood, or rent a big truck and roll on it."
According to Mia Bloom, who follows female jihadists at Georgia State University, "she was an activist for extreme violence, especially against the US military and military."
In an interview with ABC News on Feb. 19, Muthana said she was now ashamed of these publications and wanted them back. She said she felt remorse, sorrow and regret and begged to go home.
"I hope America does not think I'm a threat to them and I hope they'll be able to accept me," she told ABC.
But if she eventually returns to the United States, it may not be on her own terms.
Hassan Shibly, head of Florida's Council for American-Islamic Relations and a representative of his family, said the family understood that Muthana could be prosecuted, believed in the legal system, and demanded only due process.
The Ministry of Justice has not specified whether it will be extradited or prosecuted.
State Department spokesman Robert Palladino said Tuesday that he could not discuss his particular case, but that for all members of the Islamic State in Syria, the policy of the department "in this regard, would be to repatriate them – and that's what we call all countries to do."
Asked that members of the Islamic State could be sent to the Guantanamo Bay detention center, Palladino reportedly only said: "The US government is considering different disposition options for foreign terrorist fighters who can not be repatriated . "
According to Muthana, she escaped from the Islamic State a few weeks ago and headed to the Kurdish region of northern Syria, where she is now in a displaced persons camp. with his 18-month-old son. In her note, she talks about the future of her son.
"In my calm moments – between bombings, famine, cold and fear – I looked at my beautiful little boy and I knew that I was not from the city, and neither did he," he said. -she writes.
It's only now that she really understands how important the freedoms we have in America are. "
But Hughes, the researcher, has words of caution.
"Do not put a pink color on what she did," he said. "She joined a foreign terrorist organization."
CNN's David Shortell contributed to this report.