MINNEAPOLIS (AP) — A federal judge on Wednesday ordered defendants in all upcoming cases stemming from a major COVID-19 pandemic fraud case in Minnesota to stay away from her courtroom after allegations of witness tampering surfaced in the trial of the alleged ringleader. Prosecutors say the scheme stole $250 million from a program meant to feed children.

Aimee Bock, who founded and led the now-defunct nonprofit, went on trial this month with Salim Said, a former co-owner of Safari Restaurant in Minneapolis, for their alleged roles in the scheme. They’re among 70 defendants charged in the investigation. Many of them have already pleaded guilty. The others are being tried in batches.

U.S. District Judge Nancy Brasel imposed the restrictions a day after Assistant U.S. Attorney Joe Thompson made the allegation. He said in court after testimony ended Tuesday that the alleged attempt was especially troubling in light of an attempt in June to bribe a juror in the first trial of defendants in the sprawling fraud case, which centers on a group called Feeding Our Future.

Prosecutors have called it one of the country’s largest pandemic-related fraud cases. The first trial was marred by an alleged attempt by some defendants and people linked with them to bribe a juror with a bag of $120,000 in cash. The juror went straight to police.

“Here we find ourselves again with people trying to corrupt our process,” Thompson told the judge.

Thompson said a defendant who’s slated for trial later this year, Abdinasir Abshir, approached a witness in the courthouse hallway while testimony was underway Tuesday and asked to speak with him in a bathroom. That witness, Sharmake Jama, the former owner of Brava Cafe in Rochester, pleaded guilty earlier along with four family members and agreed to testify against Bock and Said. Jama told his lawyer about the approach, who in turn informed the U.S. Attorney’s Office.a

“I just want to be clear — witness tampering is a crime and a serious one,” Brasel said. “And that’s what we are trying to prevent here. I don’t know what occurred here today but I am going to find out.”

Brasel said she would interview Jama about the incident along with a federal marshal who witnessed some of the conversation, and one of the prosecutors.

In her order Wednesday, Brasel said all defendants charged in the upcoming cases must contact her chambers 24 hours in advance if they want to attend the current or other trials. This would allow the court to set up an overflow viewing location on a different floor of the federal courthouse in Minneapolis. She prohibited those defendants from coming to the floor where her courtroom is located.

Abshir’s attorney, Craig Cascarano, said Wednesday that his client never intended to intimidate any witness and didn’t even know that Jama was a potential witness. He said Abshir recognized him during a chance encounter in the hallway and just wanted to express his condolences over the recent deaths of Jama’s mother and sister.

The judge on Tuesday ordered Said and Bock not to speak with any witnesses or co-defendants in the case. The two are not in custody, and Brasel threatened to jail them if they violated the order.