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The Trump Instagram video featured ominous music as it questioned Carson's claims of having a violent childhood.
"Violent criminal? Or pathological liar?" the ad asked. "We don't need either as president."
Trump has sharply escalated his criticism of Carson in recent days as the retired neurosurgeon rose in the polls and challenged Trump's front-runner status in the Republican primary.
Watch Trump's video below:
Trump has repeatedly questioned the claims made in Carson's autobiography, "Gifted Hands."
In an epic Thursday-night speech in Iowa, Trump raged against Carson's account of having a violent childhood roughly 50 years ago. In particular, Trump latched onto Carson's description of having a "pathological temper" that he overcame in order to become a world-renowned brain surgeon.
"He goes into the bathroom for a couple hours, and comes out, and now he's religious," Trump said Thursday. "And the people of Iowa believe him. Give me a break. Give me a break. It doesn't happen that way. It doesn't happen that way."
Trump repeatedly compared Carson's supposedly incurable temper to child molesters.
"If you're a child molester - a sick puppy, you're a child molester - there's no cure for that," he said. "There's only one cure. We don't want to talk about that cure. That's the ultimate cure."
But at the same time, Trump also cast disbelief on the decades-old violent episodes described in Carson's book. His Instagram video on Friday highlighted a CNN investigation that could not find people who knew Carson as an angry young teenager.
For his part, Carson reportedly responded to Trump's Thursday-night rant by simply saying: "Pray for him."