(CNN) -- The FBI accuses a 20-year-old Florida man of giving online advice on how to build a bomb that could be detonated at a 9/11 event in Kansas City, Missouri, federal authorities said Thursday.
Joshua Ryne Goldberg of Orange Park, Florida, was arrested and charged with distribution of information relating to explosive, destructive devices and weapons of mass destruction, U.S. Attorney A. Lee Bentley III of the Middle District of Florida said in a news release.
According to a criminal complaint, Goldberg posed online as "Australi Witness" and "AusWitness," a Muslim living in Australia who was promoting jihad around the world.
The FBI said it became aware of him through Twitter messages under the Australi Witness handle that encouraged attacks on the Muhammad Art Exhibit and Contest in Garland, Texas, in May. Two men who attacked the exhibit were shot to death by police.
An FBI confidential source began communicating with him through a direct messaging application, the complaint says, and Australi Witness discussed building a pressure cooker bomb that could be detonated at the Kansas City Stair Climb, a September 13 event in which firefighters honor New York City firefighters killed in the 9/11 terrorist attacks, the complaint said.
Australi Witness provided links to five websites with bomb-building instructions and urged the FBI source to put nails, glass and metal into the bomb, the complaint says. He instructed the FBI source "to dip the screws and other shrapnel in rat poison in order to inflict more casualties," the complaint states.
"I haven't made one before, but I've studied how to make them," AusWitness said in one piece of dialogue quoted in the complaint. "Get FAR away from the bomb, brother. There's going to be chaos when it goes off. Shrapnel, blood and panicking kuffar will be everywhere." (Kuffar is a derogatory term used to describe non-Muslims).
Goldberg confessed when agents raided his home, the complaint said. He said he planned to notify authorities before the bomb was detonated so he could be a hero, the complaint said.
If convicted, he could be sentenced to 20 years in prison.
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