Jamal Khweis, Mohamad Jamal Khweis’s father, speaks to reporters outside his home in the Alexandria area. (Matt Zapotosky/TWP)

The American man who was reportedly fighting for the Islamic State before turning himself in to Kurdish forces in Iraq was a 2007 graduate of Fairfax County’s Edison High School who, by the accounts of some who knew him, showed no violent tendencies or signs of religious fanaticism.

Mohamad Khweis — known to high school classmates as “Mike” or “Mo” — was not even on the FBI’s radar until he was picked up in Iraq. FBI agents have since launched an investigation into the matter, officials familiar with the case said.

Many details remain unclear. A relative told The Washington Post that Khweis, 26, went on vacation to Greece and Turkey about two months ago with some friends, and an uncle gave a similar account to NBC News. On Monday, Kurdish peshmerga authorities told the Associated Press, the Guardian and others that their forces shot at Khweis, who was lingering near the town of Sinjar and was thought to be a suicide bomber, and Khweis soon gave himself up.

The Kurdish publication Rudaw, citing a local commander, said Khweis entered Syria from Turkey two months ago, had traveled to Mosul and was on his way back to Turkey when he was captured. The commander identified Khweis by a different name, though a Virginia driver’s license he was carrying bore the name “Mohamad Jamal Khweis” and a credit card said “Mohamed J. ­Khweis.” Khweis is currently being held by peshmerga forces for ­interrogation.

A U.S. State Department spokesman said the department was working with local authorities to confirm reports that an American citizen was taken into custody.

Harrison Weinhold, 27, of Alexandria, said that he attended Fairfax County’s Mark Twain Middle School with Khweis and that the two graduated from Edison High School in 2007. Weinhold said he instantly recognized Khweis in pictures and videos broadcast by news outlets.

“I’m like, ‘I can’t even comprehend what I’m looking at right now,’ ” Weinhold said. “It could not have been a more normal guy.”

Weinhold said Khweis is the soft-spoken son of a limo driver and a cosmetologist and was known to wear designer Jordan shoes. Although some people in the school were devout Muslims, Khweis was not one of them, Weinhold said.

“He was somebody that joked around and even made fun of ­people that were super-religious,” Weinhold said.

Weinhold said that in the time he spent at Khweis’s home, ­Khweis and his family spoke English. He said he ran into Khweis in Springfield, Va., about a year and a half ago and nothing seemed amiss.

Another high school friend, who spoke on the condition of anonymity to protect her privacy, said that Khweis “was friendly and goofy and made jokes” and that news of his detainment by Kurdish forces was “very shocking.” She noted, though, that she had not spoken to Khweis in many years and that a Facebook profile he once maintained was no longer visible to her.

A Fairfax schools spokesman confirmed that a man named Mohamed Khweis graduated from Edison in 2007. Jamal Khweis, ­Khweis’s father, told reporters outside his home Monday that his son was “a good person. He’s a good son,” though he declined to detail when his last contact with the young man was.

“He’s old enough. I cannot ask him where he’s going, where he’s coming from,” he said.

A congressional report released late last year said that more than 250 people from the United States had joined or attempted to join extremist groups fighting overseas and warned that “many of them are only a plane-flight away from our shores.”