The Gadianton judges have a vested interest in discrediting Nephi as a prophet, since he has prophesied against them directly. (See commentary accompanying Helaman 8:1.) If Nephi is vindicated as a prophet, then the people might remove the judges from power on Nephi’s word alone, thus making a self-fulfilling prophecy. They quickly present an alternate explanation: not prophecy but conspiracy. Nephi knew about the deed, not because of divine revelation, but because he had instigated the murder.