However, the indictment remained sealed and further details on the charges were unavailable.
Assistant U.S. Attorney Geoff Barrow said the documents would be unsealed within 24 hours.
Barrow said the indictment was returned against the 11 people who have already been arrested and others, perhaps a reference to the last four holdouts at the Malheur National Wildlife Refuge.
Defense attorneys demanded the immediate unsealing of the indictment — a request denied Wednesday by U.S. Magistrate Judge Janice Stewart.
"You will get a copy of the indictment in due course, don't worry," Stewart said. Arraignment was set for Feb. 24.
Authorities arrested 11 people last week on a criminal complaint charging them with felony conspiracy. They were accused of using intimidation to prevent federal officers from doing their work at the refuge in sparsely populated southeast Oregon.
In a criminal complaint, defendants have a right to a preliminary hearing in which they can question the arresting officer under oath about probable cause for the charges.
After an indictment, they are no longer entitled to such a proceeding.
The cancellation of preliminary hearings that had been scheduled for Wednesday dismayed attorneys for the accused.
Lisa Hay, who represents defendant Ryan Payne, said it appears prosecutors moved to scrap the hearings even before the indictment had been handed down. She was also annoyed that prosecutors presented the indictment to the judge and not to defense attorneys.
"That's an unusual thing and it's unfortunate in a case like this, where many of the people distrust the government to begin with," Hay said.
The occupation began Jan. 2, with the group demanding the federal government turn public lands over to local control. While most of the occupiers have been arrested, four have refused to leave, despite Bundy's urging.
They have said they want assurances they won't be arrested. The remaining occupiers are David Fry, 27, of Blanchester, Ohio; Jeff Banta, 46, of Elko, Nevada; and Sean Anderson, 48, and Sandy Anderson, 47, a married couple from Riggins, Idaho.
The government is building a case to show the occupation was a threat to residents and federal employees. Prosecutors say the group was ready to use violence to hold on to the refuge.
Defense attorneys have said their clients engaged in civil disobedience and are being punished for political speech. They say the only use of force during the standoff was by police, who shot and killed occupier Robert "LaVoy" Finicum during a Jan. 26 traffic stop. Bundy and others were then taken into custody.
Federal authorities have released aerial video and said Finicum was going for a gun in his jacket pocket.
In a separate matter, an attorney for Shawna Cox — a defendant allowed to return home to Utah as her case goes through the court system — asked Wednesday for her client to be allowed to attend Finicum's funeral on Friday. The funeral is in the same town where Cox lives.
Judge Stewart denied the request.
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