Forgive me if this has been asked before but as far as I am aware we see Voldemort's actions through Harry - he sees Grindelwald refusing to tell Voldemort where the wand is and then the next thing we see is Voldemort at Hogwarts walking towards Dumbledore's grave and stealing the wand.
But is it ever 100% explained how Voldemort knew the wand was in Dumbledore's grave?
Is he just making a logical guess seeing as Dumbledore was well known for defeating Grindelwald and therefore assumed that he might have taken possession of the wand?
Or perhaps did Snape tell Voldemort? Maybe to curry favour with the Dark Lord, knowing that the wand's power had either died with Dumbledore, had passed to himself or even Draco?