The judge overseeing Donald Trump’s hush money trial briefly closed the courtroom on Monday, forcing reporters into the hallway after he admonished a defence witness for his behaviour on the witness stand.

It happened minutes into the testimony of Robert Costello, a former federal prosecutor who has publicly blasted the prosecution’s star witness, Michael Cohen.

Trump is the first ex-president on criminal trial. Here’s what to know about the hush money case.

Costello aggravated Judge Juan M. Merchan repeatedly in his testimony by making comments under his breath and continuing to speak after objections were sustained – a signal to witnesses to stop talking. At one point, Costello remarked “jeez” when he was cut off by an objection. He also called the whole exercise “ridiculous.”

After excusing the jury, Merchan told Costello: “If you don’t like my ruling, you don’t say ‘jeez’ … You don’t give me side eye, and you don’t roll your eyes.”

Reporters were taken aback that they were being shooed out of the courtroom amid proceedings in the historic trial. They were allowed back in after about five minutes.

The prosecution rested its case earlier on Monday after several days of testimony from Cohen, Trump’s loyal attorney-turned-adversary who the defence sought to paint as a serial fabulist who is on a revenge campaign aimed taking down Trump.

Costello, a former federal prosecutor in New York, is relevant to the case because of his role as a Cohen antagonist and critic in the years since their professional relationship splintered in spectacular fashion.

Costello had offered to represent Cohen soon after the lawyer’s hotel room, office and home were raided and as Cohen faced a decision about whether to remain defiant in the face of a criminal investigation or to cooperate with authorities in hopes of securing more lenient treatment.

Costello testified that Cohen told him Trump “knew nothing” about the $130,000 hush money payment to porn actor Stormy Daniels that’s at the centre of the case.

“Michael Cohen said numerous times that President Trump knew nothing about those payments, that he did this on his own, and he repeated that numerous times,” Costello told jurors.

Over several hours of cross-examination, Trump’s attorneys tried to sow doubt in jurors’ minds about Cohen’s crucial testimony implicating the presumptive Republican presidential nominee in the hush money scheme. Defence lawyers seized on Cohen’s past lies and criminal history, underscoring the risk of prosecutors’ reliance on the now-disbarred attorney.

Cohen testified earlier on Monday that he stole tens of thousands of dollars from Trump’s company, an admission defence lawyers hope to use to undermine Cohen’s credibility as a key prosecution witness in the former president’s hush money trial.

Cohen claimed to have paid $50,000 to a technology firm for its work artificially boosting Trump’s standing in a CNBC online poll about famous businessmen. Cohen said he gave the firm only $20,000 in cash in a brown paper bag, but he sought reimbursement from Trump for the full amount, pocketing the difference.

“So you stole from the Trump Organization?” defence attorney Todd Blanche asked.

“Yes, sir,” Cohen replied. Cohen said he never paid the Trump Organization back. Cohen has never been charged with stealing from Trump’s company.

Cohen is a key witness but also a complicated one. He admitted on the witness stand to a number of past lies, many of which he claims were meant to protect Trump. Cohen also served prison time after pleading guilty to various federal charges, including lying to Congress and a bank and engaging in campaign-finance violations related to the hush money scheme. He has made millions of dollars off critical books about the former president, whom he regularly slams on social media in often profane terms.

But when pushed by Blanche, Cohen stood by his recollection of conversations with Trump about the hush money payment to Daniels that’s at the centre of the case.

“No doubt in your mind?” Blanche asked about whether Cohen specifically recalled having conversations with Trump about the Daniels matter. No doubt, Cohen said.

Prosecutors got another shot to question their star witness after the defence wrapped up their cross-examination. Prosecutor Susan Hoffinger took a dig at the defence strategy to go after Cohen, asking him: “I know you might feel like you’re on trial here after cross-examination, but are you actually on trial here?”

“No, ma’am,” Cohen replied.

After more than four weeks of testimony about sex, money, tabloid machinations and the details of Trump’s company recordkeeping, jurors could begin deliberating as soon as next week to decide whether Trump is guilty of 34 felony counts of falsifying business records in the first criminal trial of a former US president.

The charges stem from internal Trump Organization records where payments to Cohen were marked as legal expenses. Prosecutors say they were really reimbursements for the payment to Daniels to keep her from going public before the 2016 election with claims of a sexual encounter with Trump. Trump says nothing sexual happened between them.

Trump has pleaded not guilty. His lawyers say there was nothing criminal about the Daniels deal or the way Cohen was paid.

“There’s no crime,” Trump told reporters after arriving at the courthouse on Monday. “We paid a legal expense. You know what it’s marked down as? A legal expense.”

Trump’s allies, including several who joined him at the courthouse on Monday, quickly seized on Cohen’s admission on the witness stand. Former Trump administration official Kash Patel told reporters that Monday marked the first time in six weeks of trial proceedings that “we finally have a crime” – Cohen stealing money from the Trump Organization.

“We also have a victim. That victim is Donald J. Trump,” Patel said.

Known for his hot temper, Cohen remained mostly calm on the witness stand despite sometimes heated interrogation by the defence about his misdeeds and the allegations in the case.

Prosecutors will have an opportunity to call rebuttal witnesses once Trump’s witnesses are done. Judge Juan M. Merchan, citing scheduling issues, said he expects closing arguments to happen on May 28, the Tuesday after Memorial Day.

Defence lawyers said they have not decided whether Trump will testify. And Trump did not respond to shouted questions from reporters about whether his lawyers have advised him not to take the stand. Defence attorneys generally are reluctant to put their clients on the witness stand and open them up to intense questioning by prosecutors, as it often does more harm than good.

• An AP report