With the exception of an appearance before Congress last year, James Comey has largely kept his own counsel since being fired as FBI director.
On Sunday, ABC News broadcast a one-hour interview with Mr Comey - edited down from five hours of footage, we are told - ahead of publication of his memoir, A Higher Loyalty, on Tuesday.
In it he discussed everything from his handling of the investigation of Hillary Clinton's email server to his meetings with Donald Trump in the Oval Office.
Here are the seven key quotes.
1. On Donald Trump's fitness for office
"I don’t buy this stuff about him being mentally incompetent or early stages of dementia. He strikes me as a person of above average intelligence who’s tracking conversations and knows what’s going on. I don’t think he’s medically unfit to be president. I think he’s morally unfit to be president.
"A person who sees moral equivalence in Charlottesville, who talks about and treats women like they’re pieces of meat, who lies constantly about matters big and small and insists the American people believe it — that person’s not fit to be president of the United States, on moral grounds."
2. On obstruction of justice
"Possibly. I mean, it's certainly some evidence of obstruction of justice. It would depend and-- and I'm just a witness in this case, not the investigator or prosecutor, it would depend upon other things that reflected on his intent."
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3. On 'the business with the prostitutes'
"I didn't ask about the business with the prostitutes, but he launched into an explanation as to how I should know that wasn't true and that he remembered now, from talking to friends who had been with him, that he'd never stayed overnight at the hotel, he'd just changed clothes there and went to the Miss Universe pageant.
"I don't know whether any of this true, but this is what he said. And then went right back without staying overnight. And then he said, 'Another reason you know it's not true is I'm a germaphobe. There's no way I'd let people pee on each other around me.' And that me caught me so much by surprise I actually let out an audible laugh and - 'cause it was just one of those - I was startled by it.
"And - and I remember thinking, 'ell, should I say that, 'As I understand the activity sir, it doesn't require an overnight stay. And given that it was allegedly the presidential suite at the Ritz Carlton, I would imagine you could be at a safe distance from the activity -' all these things are bouncing around my head. But instead of saying it, it just led me to think, 'The world's gone crazy.'"
4. On whether the Russians have kompromat on the president
"I think it's possible. I don't know. These are more words I never thought I'd utter about a president of the United States, but it's possible."
5. On similarities to a mob boss
"I’m not trying to, by the way, suggest that President Trump is out breaking legs and — you know, shaking down shopkeepers. But instead, what I’m talking about is that leadership culture constantly comes back to me when I think about my experience with the Trump administration. The — the loyalty oaths, the boss as the dominant center of everything, it’s all about how do you serve the boss, what’s in the boss’s interests. It’s the family, the family, the family, the family. That’s why it reminds me so much and not, 'So what’s the right thing for the country and what are the values of the institutions that we’re dealing with?'"
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6. On Donald Trump's hands
"I say that in my book cause I’m trying to be honest, cause that’s the truth there had been all this controversy and mocking about hand size, I can’t remember the details. But as I shook his hand I made a note to check the size and it seemed like he had average-sized hands."
7. On Mr Trump's staff as 'enablers'
"That is the question that people have to ask themselves. And-- and there's no easy way to define it in the abstract, that you-- the challenge of this president is that he will stain everyone around him. And the question is, how much stain is too much stain and how much stain eventually makes you unable to accomplish your goal of protecting the country and serving the country? So I don't know. And it would be hard for anybody to answer that. But everyone's gotta answer that individually."