U.S. District Judge Patrick Walsh ruled Nna Alpha Onuoha, 29, a flight risk and ordered him held without bond. Onuoha did not enter a plea.
The Nigerian-born, naturalized U.S. citizen faces felony charges in connection with the threats -- depicted in phone calls, suspicious packages and rambling letters -- which unfolded Tuesday morning after he resigned his TSA job at the Los Angeles airport.
According to a federal affidavit, Onuoha returned to LAX about four hours after he resigned, leaving behind a package containing an eight-page letter about his complaints over a June incident that led to his suspension.
Onuoha then allegedly made three calls to airport officials, warning that the "TSA was running out of time" and the "entire airport" should be evacuated immediately.
Authorities went to the Onuoha's Inglewood apartment -- where the former National Guard infantryman lived in a complex designated for military veterans -- but found no sign of him. Onuoha was gone, along with his belongings, authorities said.
The only thing left behind, according to the affidavit, was a handwritten note in his closet, reading: "09/11/2013 THERE WILL BE FIRE! FEAR! FEAR! FEAR!"
The multiagency search for Onuoha ended late Tuesday night, when a security guard spotted the suspect sleeping in a van parked at Harvest Christian Fellowship in Riverside. He was arrested by a Riverside Police SWAT team without incident, "oblivious" to the search, Lt. Guy Toussaint said.
When Onuoha was arrested, he told authorities that his intentions weren't a call to violence, according to the affidavit. Instead, he said, he planned to start "preaching in the streets."
The letters also mentioned the June incident that led to Onuoha's weeklong suspension a month later.
Onuoha, who had worked for the TSA since 2006, was suspended from July 21 to July 27 for criticizing a 15-year-old girl's choice of clothes, telling her to "cover up," according to the federal affidavit. The encounter was highly publicized after the girl's father -- BoingBoing blog founder Mark Frauenfelder -- wrote about the incident.