Why it’s nearly impossible for Trump to kill the Russia investigation.

While fears that President Donald Trump might oust Deputy Attorney General Rod Rosenstein and special counsel Robert Mueller have ebbed in recent days, concerns remain about the long-term fate of the Russia investigation. MSNBC’s Rachel Maddow argued last night that Mueller has taken steps to make sure it could continue without him.

It’s not clear if Mueller’s actions are a conscious effort to entrench the investigation beyond the special counsel’s office. Given the investigation’s scope, there are legitimate reasons for him to liaise with the National Security Division and other key offices in the Department of Justice. The Manafort investigation also has deep roots in the federal prosecutor’s office in eastern Virginia that precede Mueller’s appointment.

The Russia investigation is not immortal, but it is very hard to kill. Whether and how it would die depends on the whims of the president and the integrity of DOJ personnel who respond to them. Former FBI Director James Comey made a similar point in an interview with Maddow last week.

“If somebody did want to end the Mueller investigation, how would they do it?” she asked him.

“I actually don’t think you could accomplish that by firing Director Mueller,” he replied. “I think you’d have to fire everybody in the FBI and the Justice Department to accomplish that in practice, given the commitment of the people in those organizations.”

Jack Goldsmith, a former DOJ official in the George W. Bush administration, argued in January that DOJ’s culture of independence would make it hard to find a willing executioner for the Russia investigation, and that even pardons wouldn’t be able to halt its progress. “They wouldn’t stop the Justice Department from reporting Mueller’s findings to Congress under the special counsel regulations,” he wrote. “They wouldn’t stop related state prosecutions. And they would be political dynamite that would destroy Trump’s presidency.”

Even if Trump succeeds in purging the Justice Department, he can’t force Rosenstein and Mueller to unlearn whatever they’ve learned so far. There’s always the risk that Mueller could simply tell Congress and the American people what he found out if he’s fired prematurely. And Comey’s book tour underscores that some Justice Department personnel could do far more political damage from the outside than from within.