LOS ANGELES (AP) — Federal authorities said Thursday they believe a former Los Angeles airport security screener acted alone and there wasn’t a larger plot when he made threats that closed some airport terminals on the eve of the anniversary of the 9/11 terrorist attacks.

Investigators haven’t found any explosives or weapons belonging to screener Nna Alpha Onuoha, 29, who was charged Wednesday, the day after quitting his job with the Transportation Security Administration at Los Angeles International Airport.

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Authorities said there is no evidence at this point to show Onuoha was aided in his efforts or there was a bigger terror plot brewing.

“We have no indication there was anyone else involved in this,” said FBI Special Agent in Charge David Bowdich.

A manhunt was launched on Tuesday after authorities say Onuoha resigned from his job and returned several hours later to leave a package at TSA’s airport headquarters that was addressed to a manager. He is originally from Nigeria and formerly served in the National Guard.

A bomb squad found no explosives or harmful contents in the package but discovered an eight-page letter in which Onuoha expressed disdain for the U.S. and referenced the event that led to his suspension, investigators said.

Onuoha, who had worked for TSA since 2006, was suspended for a week in July following an incident at LAX where he allegedly told a 15-year-old girl to cover up.

The incident drew attention when the girl’s father, Mark Frauenfelder, wrote about it on his blog. He said his daughter was humiliated and shamed. He posted a photo of her in the outfit, modest by modern standards, and said he had complained to TSA.

Onuoha referenced the suspension in a lengthy letter apparently written to Frauenfelder that was found on a website that has other postings with Onuoha’s name and birth date that matches public records for him. Authorities are examining the website that also has passages declaring America would be “reduced to nothing.”

“Do not expect another 9/11,” the posting attributed to Onuoha said. “What will unfold on this day and on the days ahead will be greater than 9/11.”

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In a search of Onuoha’s apartment, police found a handwritten note entitled “9/11/2013 THERE WILL BE FIRE! FEAR! FEAR! FEAR!” and containing unspecified threats that cited the anniversary of the terror attacks, authorities said.

An FBI affidavit says Onuoha told investigators he didn’t mean the calls to the airport to be threats and he had no violent intentions. He said he wanted to start preaching in the streets beginning Wednesday, the anniversary of the 9/11 attacks.

A phone message left for defense attorney Samuel Josephs was not immediately returned Thursday.

Onuoha had served as an infantryman in the National Guard from 2004 to 2010, including a deployment to Kosovo for a peacekeeping mission between 2005 and 2006, said California National Guard spokesman Capt. Will Martin. Onuoha reached the rank of specialist.

Onuoha made his initial court appearance Wednesday but didn’t enter a plea to one count each of making a false threat and making threats affecting interstate commerce. If convicted, he could face up to 15 years in prison.

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