A federal grand jury has indicted the 20-year-old Savage, Minn., man arrested last month as he tried buying grenades and gun parts from an FBI informant that he allegedly said were in preparation for the mass killing of police.

The two-count indictment against River William Smith arrived Thursday amid fresh arguments from prosecutors against a bid from Smith's attorney to have him released from custody before trial.

Smith is now charged with one count of unlawful possession of a machine gun and one count of attempting to receive or possess unregistered destructive devices. FBI agents arrested Smith on Dec. 14 as he attempted to buy three grenades and three auto sear devices that could convert pistols into fully automatic weapons.

In new court filings this week, prosecutors continued to link Smith to a desire to join Nazi paramilitary groups and threats against law enforcement and the LGBTQ community, while expressing concern that relatives could further steer him to violent behavior were he to be released.

"[Smith] was and remains a danger to law enforcement officers and to the community at large," assistant U.S. Attorney Manda Sertich wrote in a Thursday memo arguing against Smith's motion to be released from jail.

Smith's attorney, Jordan Kushner, said in an email Friday that the allegations against Smith "are exaggerated and based on statements taken out of context."

Kushner argued in a Dec. 29 filing that the government "failed to produce reliable evidence to support a conclusion by clear and convincing evidence that Mr. Smith presents a danger to the community."

Kushner has pointed out that Smith had no criminal history or history of violence and that Magistrate Judge Elizabeth Cowan Wright "erroneously accepted double or triple hearsay statements which were reportedly snippets of conversations without any further context that insinuated that Mr. Smith approved of violence or planned to engage in a violent confrontation with police."

Prosecutors are contending that no set of release conditions could ensure community safety, and Wright reached that conclusion after Smith's detention hearing last month.

According to court documents, Smith's arrest took place "without incident" last month. At the time, he was wearing soft armor and possessed a loaded Glock handgun with a bullet in the chamber and additional magazines. Afterwards, agents recovered from his vehicle an AR-style rifle, thousands of rounds of ammunition in magazines, body armor, ballistic helmets with goggles and plates, edged weapons for fighting in close quarters, targets, and a battle belt.

Agents noted that when they searched his home that same day, Smith's grandmother first told them there were no weapons at the home before his grandfather corrected her. Law enforcement found firearms and a "Black Sun" flag near Smith's bedroom that prosecutors say is affiliated with neo-Nazi groups.

Wright previously noted that she considered releasing Smith to reside with and be monitored by his grandmother but noted that she did "not appear to be steering [Smith] towards lawful conduct or deterring [him] from unlawful conduct." The judge also considered the possibility of a halfway house but found that there was not "sufficient structure to assure the safety of the community given the nature and seriousness of the danger, including threats of shootings."

Smith first landed on law enforcement radar when, at 17 years old in 2019, he discharged an AK-47 in the home he shared with his grandparents in Savage. His grandmother was struck in the hand with debris or fragmentation, according to court records. Police found several handguns, a rifle, shotgun, magazines, tactical equipment and ammunition during a search of the home. And law enforcement turned up searches relating to Hitler and Nazis, files related to bomb-making and videos of gay people being killed during a search of his electronic devices.

The FBI began tracking Smith after two people reached out in September 2022 to express concern about his behavior at a shooting range, namely that he would fire off large volumes of ammunition around barriers while wearing body armor and lying on the ground.

The FBI collected text conversations between Smith and two informants late last year leading up to his arrest. During that time, he described preparations to fight and die in gun battles with police. Smith also discussed how he had wanted to join a neo-Nazi paramilitary group but was deterred when he read reports of its dismantling by law enforcement. And when asked about the shooter behind a deadly attack on a Colorado Springs LGBTQ night club, Smith wrote: "I think the guys a hero."

Prosecutors said that Smith's grandmother purchased more than a thousand rounds of ammunition for Smith from one store in fall 2022. Video surveillance showed him picking out the ammunition and giving it to his grandmother for purchase, according to court documents.

In a recorded jail call with his grandmother later that night, he described 15 agents "draw on me" when they moved in to arrest him.

"Maybe I should've … I didn't even have an option to do anything bad," he said, according to a partial transcript of the jail call.

"Well, no, no, it's good that you didn't," his grandmother replied. "It's good that you are safe. OK, this too will pass, alright."

Of one of the informants, she later added: "I never did trust that guy."

"He was with them somehow," Smith said.