Robert J. Costello was the main witness Donald J. Trump’s lawyers called in his criminal trial, and like Mr. Trump, he has great disdain for the prosecution and its case.
During his brief time on the stand Tuesday, Mr. Costello had tense exchanges with Susan Hoffinger, the prosecutor cross-examining him, as they sparred for a second straight day.
Mr. Costello’s testimony centered on his relationship with the prosecution’s star witness, Michael D. Cohen. Mr. Costello, a prosecutor turned defense lawyer, was an informal adviser to Mr. Cohen, the former president’s onetime fixer. Mr. Cohen had made a $130,000 hush-money payment to a porn star on the eve of the 2016 election to silence her account of a sexual encounter with Mr. Trump.
Mr. Cohen testified that Mr. Trump had ordered him to buy the silence of the woman, Stormy Daniels. And he said that he suspected that Mr. Costello was trying to ensure that he would not cooperate with prosecutors after the hush-money deal came to light in 2018. Mr. Costello, Mr. Cohen noted, was close with Mr. Trump’s lawyer at the time, Rudolph W. Giuliani.
On Tuesday, Ms. Hoffinger echoed that claim, suggesting that Mr. Costello was actually an agent of Mr. Trump working to prevent Mr. Cohen from flipping on the then-president.
She produced a litany of emails underscoring her point, including one in which Mr. Costello wrote to his law partner, saying, “Our issue is to get Cohen on the right page without giving him the appearance that we are following instructions from Giuliani or the president.”
And once Mr. Cohen turned on Mr. Trump, pleading guilty to federal crimes for his role in the hush-money, Ms. Hoffinger noted that “you lost control of Michael Cohen for the president.”
Mr. Costello, defiant, declared: “Absolutely not.”
During her questioning, Ms. Hoffinger aimed at Mr. Costello’s credibility, seeking to turn the tables on the defense, which had called Mr. Costello to do the same to Mr. Cohen.
She began by citing Mr. Costello’s first meeting with Mr. Cohen in April 2018, and asked him to confirm that he played up his connection to Mr. Trump’s then lawyer.
“Not true,” Mr. Costello replied, prompting Ms. Hoffinger to show a pair of emails that appeared to contradict his denial.
“I told you my relationship with Rudy which could be very very useful for you,” Mr. Costello wrote Mr. Cohen two days after their meeting.
She also displayed one that Mr. Costello sent to a law partner, saying that Mr. Cohen had good reason to hire him “because of my connection to Rudy Giuliani, which I mentioned to him in our meeting.”
And when Mr. Costello equivocated about when he offered to serve as a back channel to Mr. Trump’s legal team, Ms. Hoffinger showed him an email he sent to Mr. Cohen using that exact phrase. The email recounted a conversation Mr. Costello said he had with Mr. Giuliani, who was “thrilled and said this could not be a better situation for the President or you.”
Mr. Giuliani, he added, “said thank you for opening this back channel of communication and asked me to keep in touch.”
Mr. Costello’s session on Tuesday was more placid than his combustible performance the day before.
Shortly after Mr. Costello took the stand on Monday, prosecutors objected to a series of questions. When the judge sided with them, Mr. Costello muttered “jeez,” registering his dismay and irking the judge, Juan M. Merchan. Mr. Costello tried to retract his remark, mumbling under his breath that he wanted to “strike” it from the record.
The testimony continued, but after more objections, Justice Merchan again grew frustrated. He dismissed the jury, and excoriated the witness: “If you don’t like my ruling, you don’t say, ‘jeez,’ and you don’t say, ‘strike it,’ because I’m the only one who can strike testimony in court,” he said, adding: “Are you staring me down?”
He then cleared the courtroom, dismissing reporters while allowing a group of Mr. Trump’s supporters to remain.
Then, according to a transcript, the judge told Mr. Costello that his conduct was “contemptuous” and said, “If you try to stare me down one more time I will remove you from the stand,” adding, to the defense lawyers, “I will strike his testimony, do you hear me?”
Mr. Costello asked, “Can I say something, please?” And Justice Merchan replied: “No. No. This is not a conversation.”