GEOFF BENNETT: In their new book, Pulitzer Prize-winning journalists, Carol Leonnig and Aaron Davis offer a deeply reported investigation into the decade-long unraveling of the U.S.

Justice Department.

They reveal how, under Donald Trump, the nation's top law enforcement agency was transformed from an institution built to protect the rule of law into one pressured to protect the president.

The reporting exposes how the department, already weakened by politics and fear, struggled to hold Mr.

Trump accountable after the 2020 election and how those delays may have helped pave his path back to power.

The book is "Injustice: How Politics and Fear Vanquished America's Justice Department."

And we're joined now by Carol Leonnig of MSNBC and Aaron Davis of The Washington Post.

It's great to see you both.

CAROL LEONNIG, Co-Author, "Injustice: How Politics and Fear Vanquished America's Justice Department": Thanks for having us, Geoff.

AARON C. DAVIS, Co-Author, "Injustice: How Politics and Fear Vanquished America's Justice Department": Thanks for having us.

GEOFF BENNETT: So, for anyone who has wondered how Donald Trump has so quickly transformed, reshaped, reimagined the Justice Department to serve his own political ends, this book really answers that question.

And, Carol, it started well before the start of his second term.

CAROL LEONNIG: That's right, Geoff.

We were sort of -- as reporters, Aaron and I were covering this in real time and saw Donald Trump target individual agents for humiliation, for public excoriation in his first presidency.

But what we learned in the course of reporting this book is how much that targeting and that kind of bare-knuckles attack really scarred people inside the Justice Department, and, in particular, FBI agents, who felt their careers had been tarnished, if not ruined, by him coming after them.

And it changed the tenor of a Department of Justice and a mighty investigative arm, the FBI.

It changed the tenor from one that pursued evidence of a crime without fear or favor to one that was on its back feet.

GEOFF BENNETT: Aaron, you report that Merrick Garland and Lisa Monaco took the mandate for independence so far that they slowed the January 6 and election interference investigations.

Based on your conversations with career Justice officials, did they ever perceive that Garland's caution amounted to dereliction?

AARON C. DAVIS: Well, Garland came in and was widely respected for his jurisprudence and the way he had been so even-handed on the bench as a federal judge for decades.

And they were hopeful that they would set a new tone.

And he really did from the get-go.

Merrick Garland was the guy who had actually written some of the rules about separation between the White House and DOJ and trying to keep things on the straight and narrow, much as DOJ had done after Watergate.

But there was this kind of growing concern inside the department by many, not just low ranks, but mid ranks and some people very senior, that the department was moving too slow.

And Merrick Garland had set out this mandate that we're going to start from the ground up.

We're going to build this case up from the rioters, from the video that you can see, and we will get to the top.

But there was already evidence that they were not looking at from the very get-go, and that was where the -- including the fake elector documents that had been submitted even before January 6.

And it ultimately took 15 months for DOJ and FBI to get on the same page under Garland and agreed to begin to investigate those.

GEOFF BENNETT: There is extensive reporting on the two federal cases that once faced Donald Trump, the election interference case and the classified documents case.

Carol, how do you assess the former special counsel Jack Smith's core gamble that the strength of the evidence in the classified documents case would overcome the weakness of the venue, given the concerns that Judge Aileen Cannon would ultimately derail that case, as she in fact ended up doing?

CAROL LEONNIG: You know, I want to emphasize that special counsel Jack Smith brought case -- two indictments of an unprecedented nature involving a former president in record speed.

The way he prosecuted those cases in a sprint was stunning.

But here's the gamble that you asked about.

Inside his office, there was dissension about whether or not he really should do what was legally the strongest potential way of pursuing the case, legally the most clear-cut, which was to charge in Florida.

In fact, a national security supervisor named David Newman, when he heard Jack Smith's presentation on behalf of the deputy attorney general and the attorney general, when he heard Jack Smith say we're going to bring these charges in Florida, he said, your biggest risk is you get Cannon and then this case is dead.

And it was eerie foreshadowing and an accurate forecast of exactly what happened.

Jack Smith's team believed that there was a one in six chance that they might draw Aileen Cannon, who had already shown herself to favor Trump and ignore scads of court precedent.

So they knew she was a risk.

Later on, Jack Smith's team discovered their calculations were wrong.

They had a one in three chance of getting Cannon.

There is no way we can know what would have happened if they had brought this case in D.C.

What we know is that it collapsed because of the decision to go to Florida.

GEOFF BENNETT: And there is the question of what remains.

Aaron, you say that veteran DOJ officials truly believe the department may not recover in our lifetimes.

What specific damage underpins that warning?

AARON C. DAVIS: Well, there's a couple buckets of things.

For one, so many senior prosecutors, FBI agents, the people who had worked their way up through decades, those decades of experience are gone.

There are scores and scores of prosecutors, hundreds of agents who have all left since the beginning of this administration, many under pressure to do so.

And just that body of institutional knowledge, there's been a huge brain drain inside the FBI in how they practice in protecting us as well as in the DOJ, with that experience, that understanding of, this is how we build cases, this is how we do it, this is how we do it fairly.

And all that's changed.

There's also just a -- there are so many people being brought in now who are being asked and, under a certain sense -- there's a loyalty test, we have written in the book, was administered to people who were brought in at the senior ranks of the FBI whether they supported Donald Trump or not.

And so that's just a very different way of people being promoted inside the DOJ right now.

And I think there's a real concern that we're just entering an era where politics and prosecutions could be mixed.

And, also, there's just no seeming end to this at the moment, because what does the next administration do when they come in?

If it's a Democratic one, do they keep the same people in place, as has been a stark standard of 10 years for the FBI director?

Or do they purge and bring in their own people?

And then do you continue to weaken and just have an increasingly political body of people working inside the Department of Justice?

GEOFF BENNETT: And, Carol, the loss of expertise, the loss of institutional knowledge, how does that weaken this country's defenses against terrorism and espionage?

CAROL LEONNIG: You know, Geoff, kind of the hair on my back and my neck goes up when you ask the question, because I'm thinking about some of the rooms that Aaron and I have been in with sources, people who don't talk to the press normally.

The DOJ you know, many of your viewers know is a very opaque institution.

It's secretive.

It keeps its own counsel.

It doesn't share things unless it's in public court filings.

But these people who lean conservative and careful and don't talk and squawk about their work are now coming to us and talking because they are basically crying for help.

They're saying this is a five-alarm fire, that the next terror attack, they're not sure that they're as prepared.

In fact, they feel certain they're not as prepared as they were a year ago with the lack of expertise that's gone.

One person said to me there is no imaginary security blanket around America.

It's made up with these people with this expertise and they are, as Aaron said, gone.

GEOFF BENNETT: The book is "Injustice: How Politics and Fear Vanquished America's Justice Department."

It's out today.

Carol Leonnig, Aaron Davis, always great to see you.

Thank you again for joining us.

CAROL LEONNIG: Thanks, Geoff.