How did Lord Voldemort know he had to kill Harry Potter and in which prophecy did he hear it in?

Answer 1

Actually it all starts with Dumbledore and Proffesor Trelawney. Trelawney wasnt a teacher at the time and had applied for the job. They both met at Hog's Head( a place in Hogesmade). When Dumbledore was interviewing Trelawney, she went into a trance and made the prophecy. She had only started but a Death Eater was also present at Hog's Head at the time. This Death Eater was Severus Snape. (That time he was Voldemort's true servant and not a spy for Dumbledore)Snape had heard only part of the prophecy before Dumbledore had realised he was there. Snape escaped and told Voldemort the only part he had heard(the first half). Voldemort set out to analyse the prophecy. This is all Snape had heard from Trelawney: "The one with the power to vanquish the dark lord approaches.....born to those who have thrice defied him...born as the seventh month dies...the dark lord will mark him his equal but he will have power the dark lord knows not........" Had Snape known that Voldemort would think it was Lily Potter's son, he would not have told him what he had heard.