Who is Robert Costello, the Trump witness accused of staring down judge?

All eyes turned to Robert Costello on Monday after he was called to the witness stand in former President Trump's hush money trial and was quickly admonished by the judge for his courtroom behavior.

Minutes after Costello, a former legal adviser to ex-Trump fixer Michael Cohen, took the witness stand Monday, Judge Juan Merchan asked the jurors to leave the courtroom so he could admonish Costello over his behavior on the stand.

Costello and Merchan shared a tense exchange...