From the moment Donald J. Trump began his campaign to return to the White House, he has expressed a clear desire to seek vengeance against his enemies.

He has complained relentlessly about the multiple cases filed against him during the Biden administration and has used them as a justification for seeking retribution, arguing that the Justice Department was “weaponized” against him under his predecessor.

Back in power, Mr. Trump has now weaponized the department to his own ends, critics say, in a more direct manner than any president since the Nixon era. His calls for prosecutors to file criminal charges against his adversaries have eroded the Justice Department’s decadeslong tradition of independence from the White House and threatened the rule of law.

The Justice Department, now led by Mr. Trump’s former personal lawyers, has fired dozens of career prosecutors, many of whom had worked on cases involving Mr. Trump. And the president and his allies have targeted or pushed out several U.S. attorneys as he seeks quick movement on cases involving a number of his foes.

Each of the targets Mr. Trump has pursued through the Justice Department has denied wrongdoing, in statements or through lawyers. Here is a look at them:

Indicted

What the government alleges: Over the objection of career prosecutors, Ms. Halligan filed an indictment that says Mr. Comey lied before a Senate committee in September 2020 when he denied that he authorized someone at the F.B.I. to leak to the news media. He is charged with one count of making a false statement to Congress and one count of obstructing a congressional proceeding for his testimony. Mr. Comey is set to make his first court appearance in the case on Wednesday.

Why Trump is targeting Comey: Mr. Comey led the early stages of an investigation into ties between Russia and Mr. Trump’s 2016 presidential campaign. Mr. Trump fired Mr. Comey for his involvement, which led to a fraught two-year investigation that Mr. Trump repeatedly denounced as “a witch hunt.”

Investigations underway

What the government alleges: Potential mortgage fraud related to properties owned by Ms. James. This is a tactic the administration has used against some of Mr. Trump’s political enemies, including Senator Adam B. Schiff.

Why Trump is targeting James: As New York’s attorney general, Ms. James opened an investigation into Mr. Trump on allegations that he inflated the value of his real estate holdings. She eventually secured a half-a-billion-dollar penalty against him, but it was later thrown out by an appeals court.

What the government alleges: Potential mortgage fraud related to a property in Maryland.

Why Trump is targeting Schiff: When Mr. Schiff was in the House, he helped lead the first impeachment trial of Mr. Trump in 2019.

What the government alleges: During the Biden administration, an investigation into whether Mr. Bolton had mishandled classified material gained momentum. The inquiry has continued under Mr. Trump, with the scope unclear but appearing similar to past cases involving officials accused of misusing emails or private papers related to national security secrets. Over the summer, federal agents executed search warrants at Mr. Bolton’s home and office.

Why Trump is targeting Bolton: Mr. Bolton worked as a national security adviser during Mr. Trump’s first term. But the two often clashed, and since Mr. Bolton left the post, he has often criticized the president’s stances on foreign policy.

Other targets

What the government alleges: The allegations against Mr. Brennan are hazy but appear to be related to his involvement in helping to put together an intelligence community assessment of Russian influence in the 2016 election.

Why Trump is targeting Brennan: Mr. Brennan is a former C.I.A. director whose agency’s response to Russian election interference in 2016 drew Mr. Trump’s ire.

What the government alleges: A federal grand jury has subpoenaed records related to travel that prosecutors believe Ms. Willis made abroad around the time of last year’s elections. But it is not clear the scope of the investigation nor why prosecutors were seeking the records.

Why Trump is targeting Willis: Ms. Willis is the Fulton County, Ga., district attorney who charged Mr. Trump in a sweeping case accusing him and others of seeking to overturn the 2020 election. An appeals court disqualified Ms. Willis from prosecuting the case, and it is unlikely to move forward soon.

What the government alleges: There are no specific allegations against Mr. Soros or his organization, but a memo issued to a half-dozen U.S. attorney’s offices goes as far as to list possible charges prosecutors could consider, ranging from arson to material support of terrorism.

Why Trump is targeting the Open Society Foundations: The global grant network, which has funded many liberal causes and organizations, was founded by George Soros, a billionaire Democratic donor who has long been a subject of Mr. Trump’s grievances and a boogeyman for the right. The push for U.S. attorney’s offices to investigate comes in the wake of the assassination of the conservative activist Charlie Kirk as the White House promised to crack down on liberal and progressive groups.