A hearing in Luigi Mangione’s state murder case was postponed Tuesday after prosecutors acknowledged a paperwork error, according to court officials. Mangione is expected to appear in court Wednesday for the rescheduled hearing.

“Mistakes happen. People make mistakes,” defense attorney Karen Agnifilo said Tuesday after the postponement, according to CBS News. Prosecutors said they were responsible for the delay.

Mangione faces state and federal charges in the December 2024 shooting death of Brian Thompson, the CEO of United Healthcare. He has pleaded not guilty.

The reasons for Wednesday’s hearing are not publicly known. Judge Gregory Carro scheduled it earlier in June. Carro also closed a June 3 conference to the public and the press at the request of defense lawyers, declining to provide a reason for the closure, according to ABC News.

Mangione’s trial on the state charges is expected to start Sept. 8. “Both sides should be working on a questionnaire for jury selection,” Carro said Tuesday, according to ABC News.

The judge ruled in May that a police search of Mangione was “improper” and “warrantless,” and suppressed the use of some items found in a backpack with the suspect as evidence. However, Carro said that a gun and notebook later found in a search of the backpack at a police station would be allowed. The judge in the federal case previously ruled that the backpack evidence is admissible. Mangione is expected to go on trial for the federal charges in 2027.