According to a statement from the U.S. Department of Justice unsealed Saturday, Elvis Redzepagic is charged with attempting to provide material support and resources to ISIS and the al-Nusrah Front, both designated in the U.S. as terrorist organizations.
Redzepagic was arrested Friday at his home in Commack.
A criminal complaint claims that Redzepagic twice traveled to the Middle East in a two-year period to join terrorist organization.
Redzepagic told authorities after his arrest that he'd become a devout Muslim while in Montenegro, in the Balkans, and believed a cousin was a battalion commander in Syria for the Islamic State or the group once known as the Nusra Front, according to the court complaint. The latter group -- now called the Fatah al-Sham Front, and also known at times as Jabhat al-Nusra -- is an al-Qaida affiliate.
After telling his cousin he wanted to join him, Redzepagic went to Turkey in July 2015 and aimed for Syria, first getting cab rides to the border, then directions to a border wall manned by the military, then instructions to try to cross instead by making a two-day trip through the woods, the complaint says.
But frustrated that he didn't getting more help crossing the border, Redzepagic returned to the U.S., the complaint says.
"Since I got back from Turkey from trying to perform jihad and join Jabhat al-Nusra the CIA has been bothering me," he wrote to a Facebook contact in October 2015, the complaint says. "It's annoying but I out smarted them."
CIA spokespeople didn't immediately respond to a message Saturday about the case.
He also told various Facebook contacts that "I just don't like this country," apparently meaning the U.S., and that "jihad is the best for u," according to the complaint.
"There will come a time where people will only know to say Allahu akbar," he wrote in one message, using the Arabic phrase for "God is great," the complaint says.
Then Redzepagic went to Jordan last August to try again to get to Syria, but Jordanian officials stopped him and asked why he wanted to go there. He said he wanted to study Arabic, the complaint says.
It says he then told the same to U.S. Customs and Border Protection officials, who found he had electronic files about jihad. He said he'd downloaded them two years earlier, the complaint adds. It's not immediately clear whether he remained on federal authorities' radar between then and his arrest in February, when he was released without bail on the minor charge. Long Island police notified federal authorities about the arrest.
In Facebook messages in October 2015, Redzepagic described "jihad" as fighting "for the sake of God" and "die for the sake of Allah," court documents say. He said he went to Turkey to "perform Jihad and join Jabhat Al-Nusra."
Court documents say Redzepagic admitted in interviews that when he tried to enter Syria, he was prepared to strap a bomb to himself.
Redzepagic, who is a U.S. citizen, appeared in federal court in Brooklyn Saturday. He will be held without bail and will have a bail hearing Monday in Islip.
The Associated Press contributed to this report.