Donald Trump. AP Photo/Nati Harnik In five separate Sunday interviews, real-estate mogul Donald Trump continued to stoke the controversy dogging his leading Republican presidential rival, Ben Carson.

Carson, a retired neurosurgeon, is facing scrutiny over claims made in his memoir, "Gifted Hands."

Media investigations have questioned some of Carson's accounts of his childhood and of his days as a young adult.

But Trump has homed in on the part of the book in which Carson wrote, "I had what I only can label a pathological temper — a disease — and this sickness controlled me, making me totally irrational." Carson said he later had an epiphany and became the famously soft-spoken man he is today.

In four of his Sunday interviews, Trump said Carson probably couldn't be cured of that "pathological disease."

"He said he has 'pathological disease' in the book. When you have pathological disease, that's a very serious problem because that's not something that's cured. That's something that you have to live with. And that's a very serious thing to have to live with," Trump said on ABC's "This Week."

"He talked about he has 'pathological disease.' That's a serious statement when you say you have 'pathological disease.' Because as I understand it, you can't really cure it. But he said he has pathological disease," Trump said on CNN's "State of the Union."

"Well, if you have pathological disease, that's a problem. I mean, he wrote it. I didn't write it. But he's going to have to explain a lot of things away," Trump said on NBC's "Meet the Press."

"And when you write in a book that you have 'pathological disease,' pathological disease is not cured. ... But those are pretty tough charges. And they were written by him himself, you know? The pathological stuff was written. That's very serious, pathological disease. So I just don't know what to think," Trump said on CBS' "Face the Nation."

Ben Carson. CNN/screengrab

Carson's campaigned was rocked at the end of last week by a series of reports questioning the veracity of the claims made in his memoir.

In the report on which Trump has focused, CNN couldn't find anyone who could confirm Carson's claims of attempting to attack his mother with a hammer, hitting someone with a combination lock, or trying to stab a friend as a young teenager.

Several of Carson's competitors subsequently said they thought he was telling the truth. But asked on "State of the Union" whether he believed Carson was being honest, Trump said he simply didn't know. In the same answer, Trump questioned whether a belt buckle could have stopped Carson from stabbing his friend, as Carson described in his book.

"You talk about stabbing someone and it got stopped by a belt buckle," Trump said. "Belt buckles really pretty much don't stop stabbing. They turn and twist and things slide off them. So it's pretty lucky if that happened."

Throughout his whirlwind of media interviews Sunday, Trump also repeatedly said he hoped Carson's campaign survived the controversy while at the same time suggesting there's a chance it wouldn't.

"It's a whole weird deal going on here. So I don't know," Trump said on Fox News' "Fox & Friends." "Look, I hope everything's going to be OK for Ben. I've had a good relationship with Ben. I hope it works out. I hope this isn't going to be disqualifying. And maybe it will, maybe it won't."

For his part, Carson suggested that Trump's attacks reflected unfavorably upon the billionaire businessman.

"What does it say about people who immediately jump on the bandwagon if they hear something bad rather than waiting and finding out what the truth is?" he asked on "This Week."

Pressed, Carson added: "Let me put it this way: I would not be anxious to have a commander-in-chief who acted that way."