Joshua Ryne Goldberg, 20, was arrested and charged with distributing information relating to explosives, destructive devices and weapons of mass destruction, the U.S. Attorney's Office said Thursday.
Goldberg — of Orange Park, about 15 miles south of Jacksonville — began communicating online with an undercover FBI agent in July, giving information on how to build a bomb, according to a criminal complaint. Goldberg instructed the agent to place the bomb at a memorial in Kansas City, Missouri, commemorating the 14th anniversary of the September 11, 2001, attacks, the complaint says.
Earlier this year, the agent traced online messages being used to claim responsibility for helping inspire terrorist attacks in Texas and Australia to an account in Orange Park, Fla., a few miles south of Jacksonville, according to the complaint.
According to the complaint, Goldberg began trying to help the undercover agent plan how to make a bomb.
"What weapons do you have brother? I can send you guides on how to make bombs if you need help making them," one message cited in the complaint from an account linked to Goldberg said.
Goldberg then sent bomb-making guides to the informant Aug. 19, according to the message traffic.
The next day, according to the agent, Goldberg contacted him again asking what kind of attack he wanted to carry out on Sept. 11. "I was thinking a bombing," the message reads, according to the complaint.
The informant told Goldberg, using the online alias "AusWitness," that he was a student living near Kansas City.
Goldberg claimed to be living in Perth, Australia, and said that he thought a pressure cooker bomb would be the best option and identified a 9/11 memorial event in Kansas City as the target, according to the messages.
Australian Federal Police confirmed they were contacted in relation to the investigation by the FBI. In a statement, the AFP said Goldberg will be charged with providing information online in an attempt to facilitate and encourage terrorist acts in Australia.
Two federal public defenders appointed to represent Goldberg did not immediately respond to emails seeking comment. A judge set a Tuesday bail hearing for Goldberg.
According to Australian police, they interviewed a witness who said Goldberg's online personas were part of a hoax and that the Florida man was actually a "proponent of radical free speech."