Ele provavelmente já tinha ouvido histórias sobre o Elder Wand, mas nunca ouviu a história das Relíquias da Morte. Como a história das Relíquias da Morte é considerada pela maioria dos bruxos como nada mais que um conto infantil, ele provavelmente não a encontraria em um livro escolar. Também não é provável que esteja nos livros sobre magia negra, já que, como diz Xenophilius Lovegood:
"... There is nothing Dark about the Hallows..."
Deathly Hallows, chapter 21 (The Tale of the Three Brothers)
Aqui estão os pensamentos de Harry sobre o conhecimento de Voldemort sobre as Relíquias e a Varinha dos Anciões:
Voldemort had been raised in a Muggle orphanage. Nobody could have told him The Tales of Beedle the Bard when he was a child, any more than Harry had heard them. Hardly any wizards believed in the Deathly Hallows. Was it likely that Voldemort knew about them?
Harry gazed into the darkness... If Voldemort had known about the Deathly Hallows, surely he would have sought them, done anything to possess them: three objects that made the possessor master of Death? If he had known about the Deathly Hallows, he might not have needed Horcruxes in the first place. Didn't the simple fact that he had taken a Hallow, and turned it into a Horcrux, demonstrate that he did not know this last great Wizarding secret?
Which meant that Voldemort sought the Elder Wand without realizing its full power, without understanding that it was one of three... for the wand was the Hallow that could not be hidden, whose existence was best known... The bloody trail of the Elder Wand is splattered across the pages of Wizarding history...
Deathly Hallows, chapter 22 (The Deathly Hallows)
Mas, como Dumbledore aponta, mesmo que Voldemort soubesse sobre as Relíquias e que o anel fosse uma delas, ele provavelmente não se importaria muito com isso (a menos que fosse um interesse histórico, como seu interesse pelos Hogwarts) artefatos dos fundadores.).
"And Voldemort never knew about the Hallows?"
"I do not think so, because he did not recognize the Resurrection Stone he turned into a Horcrux. But even if he had known about them, Harry. I doubt that he would have been interested in any except the first. He would not think that he needed the Cloak, and as for the stone, whom would he want to bring back from the dead? He fears the dead. He does not love."
Deathly Hallows, chapter 35 (King's Cross)
Como nota lateral, não acho que Salazar Slytherin tenha roubado o anel. O terceiro irmão não foi o único que teve descendentes. Se você está baseando isso no fato de que os outros dois irmãos morreram imediatamente na história, os irmãos já poderiam ter tido filhos antes de conhecer a Morte. Além disso, como Dumbledore sugere, a história deles se encontrando com a Morte pode nem ser verdadeira.
"So it's true?" asked Harry. "All of it? The Peverell brothers - "
" - were the three brothers of the tale," said Dumbledore, nodding. "Oh yes, I think so. Whether they met Death on a lonely road... I think it more likely that the Peverell brothers were simply gifted, dangerous wizards who succeeded in creating those powerful objects. The story of them being Death's own Hallows seems to me the sort of legend that might have sprung up around such creations."
Deathly Hallows, chapter 35 (King's Cross)
Então eu não acho que Salazar Slytherin roubou o anel. É alegado que ele é descendente do segundo irmão Peverell e não parece haver qualquer razão para duvidar disso.