It also addressed LAX passengers, as the author referenced the terminal evacuations that occurred at the airport Tuesday. Officials said a man believed to be Onuoha called the TSA twice, instructing employees to evacuate certain terminals at the airport. The caller told the employee he would be watching to make sure his instructions were carried out, Eimiller said.
Police cleared the terminals but there appeared to be no threat to the airport, Eimiller said.
The letter said the evacuations were "the only way for me to get the attention of the whole world."
"You missing your flights should be the last thing on your minds at this time," it read.
Security was increased Wednesday at LAX, Ontario and Van Nuys airports in light of the events and 9/11 anniversary, LAX Police Chief Patrick M. Gannon said.
Also Wednesday, the FBI's Joint Terrorism Task Force was searching the Harvest Christian Fellowship Church in Riverside and a van in its parking lot as part of its investigation. Onuoaha was arrested in the van, and the search was out of an "abundance of caution," Eimiller said.
"Based on the nature of the investigation, they're ruling out any threat associated with the suspect and his activity in Riverside," Eimiller said.
While searching Onuoha's apartment in Inglewood, members of the terrorist task force discovered a note taped inside a closet, Eimiller said. The note, she said, contained "an unspecified threat citing the 9/11/13 anniversary."
It appeared Onuoha had "cleared out" of the apartment before his arrest, Eimiller said.
Authorities took Onuoha's threats seriously enough Tuesday that they launched a multi-agency manhunt and considered releasing Onuoha's name to the public before he was apprehended, sources told The Times.
The TSA office near Los Angeles International Airport was evacuated for a short period Wednesday afternoon after a report of a "suspicious package"
Police evacuated an Alaska Airlines flight after a "suspicious item" was found on board.