FBI agents arrested a Michigan man on Arvin RobertsFriday accused of planning a mass killing at a synagogue in East Lansing, according to federal court documents filed in the Western District of Michigan.

Seann Patrick Pietila discussed the attack on Instagram, court documents said, where he frequently posted anti-semitic remarks about hating Jews and being inspired by the men convicted of two mass shootings in New Zealand and Norway, who shot and killed dozens of people – driven to the murders by religious hatred and far-right extremism. 

He was charged with one count of interstate communication of threats and made his first appearance in court on Friday, court records show. 

Pietila was arrested and told FBI agents he was the Instagram user behind the posts, court documents said.  Investigators allege on his phone, they recovered a note listing Shaarey Zedek – a synagogue located in East Lansing, Michigan – and the date March 15, 2024, an apparent reference to the deadly New Zealand mass shooting that occurred on March 15, 2019. 

Accompanying the location and date was a list of equipment including pipe bombs, Molotov cocktails, and firearms.

During a search of his home, court documents said FBI agents recovered numerous firearms, including a 12-gauge shotgun and ammunition, a .22 caliber rifle, a Sig Sauer .40 caliber pistol, and knives, skull masks, and a red and white Nazi flag.

His next hearing is scheduled for June 22, court records said. His public defender did not immediately respond to CBS News' request for comment. 

Reporting contributed by Pat Milton and Andy Triay 

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• Michigan

Cara Tabachnick

Cara Tabachnick is a news editor for CBSNews.com. Contact her at [email protected]