The campaign of the Republican presidential frontrunner Dr Ben Carson looked in jeopardy after he was hit by a series of allegations that parts of his life story were exaggerated and others fabricated.
Carson, a retired neurosurgeon and political newbie, described as a "witch hunt" media accusations that he lied about his college education and his violent past.
His rise from troubled, impoverished teenager in Detroit to world-renowned physician and conservative icon has been the subject of several books, a film and countless stump speeches.
But as he overtook Donald Trump in the polls last week, the only black candidate's story drew closer scrutiny. Observers and US media found discrepancies, inconsistencies and, in the latest revelations, apparent falsifications about crucial episodes in his life.
CNN published a report casting doubt on Carson's characterisation of himself in his 1996 autobiography, Gifted Hands, as a violent 14-year-old who once tried to stab a classmate. The "victim" of the episode, which Carson said was a seminal moment that led him to God, has never surfaced.