President Trump initiated a fresh attack on lawyers on Tuesday, singling out a firm where a former prosecutor who investigated him once worked as the White House pursues vengeance against the profession he blames for his legal troubles.

An executive order from Mr. Trump signed focused on Jenner & Block, a prominent white-shoe firm that once employed Andrew Weissmann, a longtime deputy to Robert S. Mueller III, who as a special counsel investigated Mr. Trump in his first term over possible links to Russia.

The order underscored the extent to which the president, who faced four criminal indictments after he left office in 2021, now aims to exact a steep price from anyone associated with past investigations of him.

Days earlier, Mr. Trump significantly expanded his campaign of retaliation against lawyers he dislikes, issuing a far-reaching memorandum that threatened to use government power to punish any firms that, in his view, unfairly challenged his administration. Mr. Trump has declared his efforts will clean up a legal profession that has become tainted by politics and unethical behavior.

At the White House on Tuesday, Mr. Trump called Mr. Weissmann a “bad guy” and said he would also declassify additional documents from the Russia investigation, known as Crossfire Hurricane, that began in 2016.

After serving in a senior role for the special counsel investigation, Mr. Weissmann spent many years as a television pundit, sharply criticizing Mr. Trump’s conduct. Mr. Weissmann, who left Jenner & Block in 2021, did not immediately respond to a request for comment.