Christopher Hasson was indicted on Feb. 27 on federal charges for unlawful possession of silencers, for possession of a controlled substance and possession of firearms by a drug addict and unlawful user.
He faces up to 31 years in prison and fines of up to $370,000.
He has not been charged with any terrorism-related counts but prosecutors previously called him a "domestic terrorist" in court filings.
When asked by reporters about a superseding indictment, Thomas Patrick Windom, who spoke on behalf of the prosecution at the hearing, said only one indictment is on the docket.
Windom said he expects to produce more evidence to the court this week, when the federal judge asked about the status of discovery.
The motions deadline was set for April 1. Hasson has been detained since his arrest on Feb. 15, and he remains in custody.
In the February hearing Jennifer Sykes, speaking on behalf of the prosecution at his last court appearance in February, said that the gun and drug possession charges were "just the tip of the iceberg" in terms of the extent of Hasson’s alleged crimes. Prosecutors said he was stockpiling weapons and "espoused extremist" and racist views for years as he sought to launch a major attack.
"The defendant intends to murder innocent civilians on a scale rarely seen in this country. He must be detained pending trial. ... The defendant is a domestic terrorist," prosecutors said in a court document filed in Maryland federal court Wednesday, when they argued that Hasson should be detained.
He is currently incarcerated pending trial and Federal Judge Charles Day said that Hasson’s internet search history, as well as previous letters and emails he had allegedly written, were enough to warrant him a danger to the community.
Hasson allegedly compiled a list of prominent Democratic congressional leaders, activists, political organizations, and MSNBC and CNN media personalities, including apparent references to Joe Scarborough, Sen. Richard Blumenthal, Rep. Nancy Pelosi, Sen. Kamala Harris, former Rep. Beto O'Rourke, and Sen. Elizabeth Warren, according to court documents.
According to court documents that said he complied that list on his work computer.
An earlier version of this story contained incorrect information about the potential prison sentence and fines. If convicted, he faces up to 31 years in prison and fines of up to $370,000. This story has been corrected.