Prosecutors working for Jack Smith, the special counsel who has twice brought indictments against former President Donald J. Trump, obtained a search warrant early this year for Mr. Trump’s long dormant Twitter account as part of their inquiry into his attempt to overturn the 2020 election, according to court papers unsealed on Wednesday.
The warrant, which was signed by a federal judge in Washington in January after Elon Musk took over Twitter, which is now called X, adds a new dimension to the scope of the special counsel’s efforts to investigate the former president.
The court papers, which emerged from an appeal by Twitter challenging the judge’s decision to issue the warrant, did not reveal what prosecutors were looking for in Mr. Trump’s Twitter account, which the tech company shut down just days after the attack on the Capitol on Jan. 6, 2021.
But the papers indicate that prosecutors got permission from the judge not to tell Mr. Trump for months that they had obtained the warrant for his account. The prosecutors feared that if Mr. Trump learned about the warrant, it “would seriously jeopardize the ongoing investigation” by giving him “an opportunity to destroy evidence, change patterns of behavior, [or] notify confederates,” the papers said.