Warren Christopher Clark, 34, appeared before a judge Friday in Houston Federal Court on an indictment accusing him of attempting to provide material support to the terrorist group. The judge ordered Clark held without bail pending a detention hearing Wednesday, according to reports.
U.S.-backed Syrian Democratic Forces gave Clark to the FBI after announcing his capture earlier this month.
The George Washington University's Program on Extremism found Clark had sent ISIS a resume seeking a job as an English teacher.
Clark noted noting that he had a bachelor's degree from the University of Houston, worked as a substitute teacher at the Fort Bend Independent School District in Sugar Land, Texas, and had done teaching stints in Saudi Arabia and Turkey, according to the documents that were obtained by the program’s researchers.
"Dear Director, I am looking to get a position teaching English to students in the Islamic State," he wrote in the cover letter. "Teaching has given me the opportunity to work with people from diverse cultural backgrounds and learning capabilities."
Clark's attorney, Michael DeGeurin, said his client would plead not guilty but declined to comment further.
The Houston U.S. Attorney Perrye Turner said Clark faces 20 years in prison if convicted.
“The FBI continues to aggressively pursue individuals who attempt to join the ranks of ISIS’s foreign fighters or try to provide support for other terrorist organizations," Turner said. "This fight against terrorism is not one we can combat alone."
Clark’s father was in the courtroom but declined comment, the Houston Chronicle reported.
The Associated Press contributed to this report.