A Kansas City man who was recently detained by authorities in Egypt is the subject of an investigation by FBI counterterrorism agents.

The FBI began investigating Isse Aweis Mohamud on April 25 after his family reported him missing, according to federal prosecutors.

Those family members told the FBI they were concerned that he had gone overseas to "engage in jihadist activities,” a prosecutor said during a court appearance for Mohamud.

Mohamud, 21, was charged with a single count of passport fraud in U.S. District Court in Kansas City last week after he returned to Kansas City from Egypt.

Federal prosecutors on Tuesday urged a judge to continue detaining Mohamud without bond in light of the terrorism investigation. He is being held by federal authorities in the Kansas City area.

But Mohamud’s attorney, Assistant Federal Public Defender Carie Allen, argued that Mohamud is not a terrorist or a danger to the community.

The judge did not rule.

The passport fraud charge says Mohamud falsely stated in his passport application that he intended to fly to Canada. Instead, he flew to Egypt without telling his family or his employer.

"There is much more to this story than the complaint would indicate on its face,” Assistant U.S. Attorney David Raskin said in an initial court appearance Friday. "There are serious questions about what in God’s name this defendant was doing leaving his family without notice and his job without notice in the middle of the day and flying to Egypt.”

According to the affidavit from an FBI agent assigned to investigate possible terrorist activity, Mohamud is a naturalized U.S. citizen born in Somalia.

He applied for his passport in January at a Gladstone post office. In the space where the application asked which countries he planned to visit, he wrote "Canada.”

Attached to the passport application was a travel itinerary for a round-trip flight from Kansas City to Vancouver, Canada, departing Feb. 8 and returning one week later.

But Mohamud never took that flight, according to the affidavit. Months later, he flew to Egypt on April 24. Shortly after his arrival, Egyptian authorities detained him in a hotel until FBI employees arrived to interview him.

When Mohamud’s family realized he had left, they reported to Kansas City police that he was missing. Police contacted the FBI after the family expressed concerns about why he left, Raskin said in court.

"They were concerned that he’d traveled to Iraq to fight with the fighters and to engage in terrorist activities,” the FBI counterterrorism agent testified in court.

Relatives said that in recent months, Mohamud had cordoned off an area in the family’s home, and behind a locked door, he was heard conversing with unknown people.

He had also "wiped clean” his internet history on several electronic devices, family members told the FBI. He left behind a letter that his mother read and later told FBI agents about while under interrogation.

Agents interviewed the cab driver who took Mohamud to the airport. He told the driver that he was going to Egypt for three months. The driver thought that it was odd because he only had a small backpack with him.

A travel agent told FBI agents that Mohamud was acting suspiciously and the government should consider revoking his passport.

A Kansas City resident told agents that Mohamud had tried to convert him and called Mohamud "the most radical Muslim he has ever met,” the FBI special agent testified in court.

The agent said he did not know why Egyptian authorities had detained Mohamud, but Mohamud was questioned by the FBI on May 1 in Cairo.

He allegedly told the FBI that he had traveled there to meet "the strangers.”

The agent testified that the term "strangers” is sometimes used to describe people who travel from other countries to fight with the Islamic State.

He said that investigators had found a 2014 conversation on a Facebook account they think is linked to Mohamud.

In that conversation, he allegedly said he wanted to travel to Syria to join the Syrian Mujaheddin and wanted to be a sniper, the agent said.

On Thursday, Mohamud flew back to the United States and was met in New York by FBI agents.

In court Tuesday, federal prosecutors told a judge that Mohamud should be detained as a flight risk and a danger to the community.

Mohamud has no driver’s license and no car, defense attorney Allen said, and is willing to surrender his passport so he would have no means to flee the country. Within 24 hours of arriving in Egypt, and learning of the FBI investigation, he booked a flight home. He would have returned then had he not been detained by authorities, Allen said.

Mohamud flew home voluntarily.

Regarding the possible danger to the community, Allen pointed to testimony that the FBI had uncovered no preparations for violent acts in the United States. The 2014 Facebook messages about fighting in Syria could not be linked to any more recent acts by Mohamud, she said.

Allen asked the judge to consider Mohamud’s possible detention or release on bond based on the charge against him and the evidence in court, and not on "radical speculation by the government.”