Seann Pietila the 19-year-old who allegedly subscribed to a neo-Nazi ideology, was indicted by a grand jury -- and the indictment offers more details about what Pietila allegedly said about carrying out a mass attack.
"I won't be taken alive, I'll make sure of that," Pietila allegedly wrote in an Instagram message to another unnamed user. "Remember 'Heil Hitler!' boom red mist."
Authorities initially charged Pietela, 19, of Pickford, Michigan, via criminal complaint with transmitting a communication containing a threat to injure another.
When they searched his home in Michigan, he allegedly had ammunition, magazines, a shotgun, a rifle, a pistol, various knives, firearms accessories, tactical vests, mask, a Nazi flag, a ghillie suit, gas masks and military sniper and survival manuals. Also seized was Pietela's phone, and in the Notes app, he had identified a particular synagogue in East Lansing, a date, and a list of equipment.
Court documents unsealed on Wednesday allege that Pietila wanted to carry out his shooting online for people "so they could screen record and send it to other people."
He also allegedly went into detail about which guns he were to use and why and expressed his disdain for Jewish persons.
In communicating with users on Instagram, he allegedly sent pictures that showed Nazi paraphernalia and were supportive of the ideology of the New Zealand shooter.
In 2019, a shooter in New Zealand killed dozens of people in back-to-back shootings at two mosques.
"The crimes alleged in this indictment have made members of our community feel unsafe as they practice their religion. No American should fear engaging in their constitutionally protected rights," said James A. Tarasca, special agent in charge of the FBI in Michigan. "I appreciate the coordinated efforts of our state and local law enforcement partners to disrupt this defendant before he could put his plans into action."
Pietila's mother, Brittany Stob, told ABC News earlier this month her son began consuming antisemitic content online when he was isolated during the pandemic and didn't have access to the mental health treatment he needed.
"He said some stuff online that he shouldn't have," she added.
But Stob asserts she believes her son is not violent and was not truly planning an attack.
"He's a good kid," she said. "He would never hurt anybody."
ABC News' Jay O'Brien contributed to this report.