After leaving in January last year, the 24-year-old was killed in November. An unknown person later messaged his family with a photo of a handwritten note from him, court documents show.
"If you're reading this then know that I've been killed in battle and am now with our Lord InshaAllah," the note said.
" I want you to know how much I love you ... but I don't think words will ever be enough to describe it."
Federal prosecutors say the man responsible for his travel to Syria is Ahmed Mohammed el Gammal. They are charging him with providing material support to ISIS and helping Goarany join the terror group in Syria.
"The charges against the defendant stem from his facilitating the travel of a 24-year-old United States citizen .... so that (he) could train and fight with" ISIS, a designated foreign terrorist organization, court documents allege.
Attorney information on the defendant was not immediately available.
Before traveling to Syria, Goarany attended college in New York, according to court documents.
Authorities said they have enough evidence against the suspect, including a YouTube video that Goarany made shortly before he died.
In the video, he confirms that he joined ISIS, but makes it clear that no one -- including Gammal -- helped him get there, according to court records.
"It was my own choice, and it was out of my own resources," Goarany said in the video. "I didn't come to this decision with anybody's influence or anybody's recruitment."
Despite his denial, the video mentions Gammal and provides evidence of their alleged relationship, federal prosecutors said. Gammal was arrested and detained without bail in August 2015.
How did they meet?
The pair's ties date to August 2014, when Goarany saw Gammal's pro-ISIS comments at a message forum online and messaged him on Facebook, the documents allege.
The two shared a series of messages and later met in New York in October of the same year. During their visit, Gammal contacted a friend in Turkey and told him an "American friend" would contact him when he arrived there.
Goarany left New York for Turkey in January last year. By February, he was in ISIS-controlled Syria, according to court documents.
In November last year, an unidentified person contacted his relatives and told them he died while fighting in Syria.