From JK Rowling World Book Day Chat - 3/4/04

[justcarol67]

No: HPFGUIDX 94585

>Ally wrote:: 
> <small snip> When Snape goes to "rescue" Harry from Sirius, he yells
at Harry and says something to the extent of: I tried to warn your
father about Sirius and he should have been grateful, but he refused
to believe me and now he's dead and you're going to wind up the same
way. [paraphrasing there just a bit]
 
If Snape thought James wound up dead b/c he didn't listen to Snape 
about Sirius, it makes sense to me that he tried to warn them at 
Godric's Hollow.  What else could it have been?  Maybe Snape got 
there just before Voldie and James sent him packing?

Carol:
I haven't checked the Shrieking Shack passage to see whether I agree
with your interpretaion of Snape's words, but I don't see how he could
have been at Godric's Hollow unless Peter personally had told him the
Secret. (He couldn't have learned it secondhand from LV or anyone
else.) And if Peter had told him, he would know that Sirius was *not*
a murderer or a traitor. In my reading of PoA, he doesn't know any
such thing. All he knows is that Lupin is a werewolf and Sirius's
former friend (whom he suspects of helping Sirius get inside Hogwarts).

You could be right that Snape tried to warn James about Sirius (whom
he wrongly suspected of being the spy) and that James rebuffed him,
but it doesn't necessarily follow that Snape was at Godric's Hollow.
(I've already presented my reasons for thinking he was already at
Hogwarts. My point here is simply that he couldn't have known that the
Potters were at Godric's Hollow (or if he somehow found that out, he
wouldn't have been able to see James to speak with him because of the
Fidelius charm).

Carol