Judge Hellerstein died on Wednesday morning, according to a court spokesman. He was appointed in 1998 and was overseeing the trial of Nicolás Maduro of Venezuela.
More than a dozen news organizations have asked a federal judge to unseal documents related to a search warrant executed at Ms. Omar’s home this month.
In the legal tangle between the Justice Department and California, a federal judge on Tuesday deferred a ruling but said the government already had a remedy it could use after the election.
In court testimony, the agent outlined the willingness of Kash Patel, the F.B.I. director, to take orders from President Trump to investigate his perceived enemies.