(CNN) — A federal judge in Alexandria, Virginia, has granted the request for five witnesses to testify with immunity in the criminal trial of former Trump campaign chairman Paul Manafort.

US District Judge T.S. Ellis is also ordering special counsel Robert Mueller’s team to tell Manafort’s team the nearly 30 witnesses it is going to use in the trial.

In addition, Ellis delayed the start of the trial, originally scheduled for Wednesday, to July 31.

A large portion of Monday’s hearing has been dedicated to discussing a “data dump” of tens of thousands of pages of documents over the past month by the government.

Manafort appeared in person at Monday’s hearing, wearing a green jumpsuit with a rumpled collar.

Attorneys for Manafort said that they needed more time to review some 120,000 pages of documents, including documents and images taken from electronic devices belonging to Manafort’s former business partner Rick Gates, that were “at the heart of the issue” in the case. Prosecutors pushed back and said most of the documents were actually images and notes from Gates’ devices — not emails.

Mueller’s team has four “phones or iPads” and one laptop belonging to Gates, who pleaded guilty earlier this year and has been cooperating with the investigation. He is expected to be a key witness in Mueller’s case.

“I’m just not sure what looking at pictures is going to do for their case,” said Uzo Asonye, a prosecutor working with Mueller’s team.

“The fact that you’re not using something does not mean it’s not usable by the defense,” Ellis responded.

The-CNN-Wire™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.