The FBI has arrested yet another American supporter of the terrorist group ISIS—but this time, it’s a 20-year-old Jewish man living at his parents’ house in Florida.

Authorities say Joshua Ryne Goldberg, a non-Muslim without previous ties to a violent jihadist movement, shared links to websites that provide instructions for making explosives to a confidential Federal Bureau of Investigation informant. Further, while allegedly posing as an Australian online, Goldberg encouraged terrorist attacks against the American public, according to a criminal complaint released by the U.S. Justice Department on Thursday.

During exchanges with the informant, authorities say that Goldberg, under the Twitter alias @AusWitness, provided links to instructions for making a bomb similar to those used in the 2013 Boston Marathon attack. The information was shared, according to the FBI, to further a terrorist plot against a 9/11 memorial ceremony in Kansas City, which would have been scheduled to take place on Sunday.

The FBI discovered Goldberg’s identity after it subpoenaed Twitter for @AusWitness’s IP address, which led them to Goldberg’s parent’s house. The account has since been suspended.

Goldberg (AusWitness) chatting with an informant (CHS) —

DOJ

Included in Goldberg’s criminal complaint are numerous chatlogs revealing interactions with the informant. On Aug. 20, he allegedly wrote: “Have you decided what kind of attack to carry out on 9/11, akhi? I was thinking a bombing. We could make pipe bombs and detonate them at a large public event.”

“Yes, I’m leaning towards that too,” the informant replied. “I’ve been getting excited about this.”

Following his arrest, Goldberg admitted to providing the informant with information on how to create explosives, and that he believed it would help build a “genuine bomb,” according to a sworn affidavit by William Berry Jr., a U.S. Customs and Border Protection officer assigned to the FBI.

“Joshua Goldberg stated that he believed that the individual did intend to create functioning bombs and would actually attempt to use them to kill and injure persons,” wrote Berry.

Goldberg made “varying statements” to explain his actions during the course of his interrogation, the affidavit says. He claimed he “intended for the individual to either kill himself creating the bomb or, if not, that he intended to alert law enforcement just prior to the individual detonating the bomb” in order to receive credit for stopping the attack.

Twitter

Prior to the foiled attack in May on an art exhibition in Garland, Texas, at which a contest was held over pictures of the Prophet Mohammed, Goldberg alleged tweeted from the account @AusWitness3 about the event and shared a map to its location.

According to Berry, the FBI had been communicating with Goldberg on a daily basis since July 26.

Illustration by Max Fleishman