(CNN) An alleged ISIS fighter from the US is a former educator in Texas who sent his resume to ISIS, according to two researchers on extremism.
The US-backed Syrian Democratic Forces announced they had captured Warren Christopher Clark, 34, who they said is also known as Abu Mohammad al-Ameriki, in Syria, though Clark's father has denied he was involved with the terror group.
The Syrian fighters said in a news release Sunday that Clark and four others were suspected of plotting an attack on civilians.
Clark's father, Warren Clark, told The New York Times that his son was "a humanitarian" and that he did not believe his son was a member of ISIS.
"My son would not be involved in anything along those lines," Clark said.
Clark also said he had never heard his son say anything that suggested he supported ISIS.
"My son doesn't have an evil thought in his mind about hurting anyone," Clark told The New York Times.
CNN has been unable to reach any of Clark's family members for comment or to confirm Clark's citizenship.
After ISIS was pushed out of Mosul, Iraq, in 2017, Clark's resume and cover letter were found in a pile of documents in a house there that was believed to have been occupied by ISIS fighters, according to Seamus Hughes and Alexander Meleagrou-Hitchens from the Program on Extremism at George Washington University, who later received copies of them from a source of theirs in Mosul. Hughes and Meleagrou-Hitchens shared copies of the resume and cover letter with CNN.
"I am looking to get a position teaching English to students in the Islamic State. I was born and raised in the United States and have always loved teaching others and learning from others as well," the cover letter says.
The letter mentions Clark's diverse teaching background and how that helped him adapt to his students' strengths. It says teaching enabled him to work with people from "diverse cultural backgrounds and learning capabilities."
According to the resume shared by the George Washington University researchers, Clark taught English as a second language in Turkey in 2015 and graduated from the University of Houston, where he majored in political science.
Mike Rosen, the executive director of media relations at the University of Houston, said someone with Clark's name and year of birth had attended the school at the years listed on the resume and had the same major, though he could not say definitively whether it was the same person.
The resume also says Clark taught English in Riyadh, Saudi Arabia, to college students and to a different class of college students training to work in the construction industry.
According to a larger George Washington University report into people from the US who joined ISIS, Clark is believed to be one of several dozen from the US among the 295 people who intelligence officials said had tried to travel or had successfully traveled to Iraq and Syria to join ISIS.
In the latest raid, the Syrian Democratic Forces said, Clark fought alongside others including Zaid Abed al-Hamid, who was also known as Abu Zaid al-Ameriki. The US-backed Syrian fighters believed Hamid to be from the United States. His nationality has not been confirmed.
Clark and the other men were planning to attack a group of civilians who were looking to flee the war zone, according to the Syrian Democratic Forces statement.
US officials have not yet confirmed that Clark was captured by the militia.
"We are aware of open source reports of reportedly American citizens currently in custody who were believed to be fighting for ISIS," Pentagon spokesman Cmdr. Sean Robertson told CNN on Monday. "However, we are unable to confirm this information at this time. The incident is under investigation."