An Iraqi-born man living in California swore that "America will not isolate me from my Islamic duty" as he used a social media account associated with the Islamic State group to plot a return to Syria, according to court documents made public Friday.

Aws Mohammed Younis Al-Jayab was indicted in Sacramento Thursday on one federal charge that he lied to investigators about traveling to Syria to fight against the government there. He was arrested last week and remains jailed, though prosecutors and his attorney say there is no indication he intended harm within the United States.

Authorities say Al-Jayab fought in Syria as a teenager before coming to the United States and went to Syria again in late 2013 and early 2014, joining a group later affiliated with the Islamic State. He faces up to eight years in prison if he is convicted of falsely telling investigators he was visiting his grandmother in Turkey.

The investigation of the 23-year-old apparently began with information from the search of a Virginia-based Facebook account in April 2014, shortly after Al-Jayab returned to the United States from his second stint fighting in Syria, according to the search warrant affidavit.

The Virginia account "appeared to be used to distribute propaganda (for) the Islamic State of Iraq and the Levant," say the court filings.

Al-Jayab used the link to communicate, in Arabic, between August 2013 and February 2014 as he planned his trip to Syria and while he was in Turkey and Syria, according to the affidavit.

"America will not isolate me from my Islamic duty," he wrote at one point. At another he warned that he was "afraid of being imprisoned in America (because) the government is alert for everything, (and) my trip here constitutes a charge."

He also used the account to communicate with an unnamed individual in Texas whom authorities have confirmed is Omar Faraj Saeed Al Hardan. Al Hardan, 24, pleaded not guilty Wednesday to three charges including that he tried to help the Islamic State group, and a federal agent testified that the Iraqi refugee sought to set off bombs at two Houston malls.

Al-Jayab's defense attorney, Ben Galloway, said he couldn't comment on the newly released material until he had a chance to review it and discuss it with his client.

"But I can say that my client had no intention of committing a terrorist act on American soil, nor did he have any intention of hurting any American citizen," Galloway wrote in an email Friday.

Al-Jayab's account included photographs of the black flag used by the al-Qaida terrorist organization and a photograph of Al-Jayab kissing the face of a dead man he addressed as "my cousin," who appeared to have been shot in the head.

There are also comments lamenting that the United States has incarcerated Sunni Muslims like himself at the Guantanamo Bay, Cuba, detention facility, and praising one of the Boston Marathon bombers, Dzhokhar Tsarnaev, shortly after the 2013 attack that killed three people and injured about 260 others.