Detecting magic (was: re AKs and Horcrux!Harry and soul-ripping )

[pippin_999]

Eloise:

> If Voldemort had the ability to cloak his activity, would really
have  broadcast to the MOM radar that he was AKing the 
Potters one by one?

Pippin:
That depends on how quickly he thought the MoM would respond. 
Not instantly, to judge by other cases. It could be that the
magical detection involves some processing time. To judge by
Harry's memories, the events at GH didn't take that long in the
first place.

I can't imagine that James, however skilled a wizard he was, could
hold off Voldemort even  as long as Dumbledore did at the MoM. 
All Voldemort had to do was believe he could finish the job before
the MoM or Dumbledore showed up. He might have arranged a
diversionary action, as well.


Eloise:
> Would GH, which we know was protected by Fidelius and where the 
 Potters had hidden with the full knowledge of Dumbledore (err,
well,  at least before the Fidelius) not be protected by other
charms? 

Pippin:
Maybe, but Voldemort would have had to disable them to get
through himself. 

Eloise:
> I find it very hard to believe that the MOM radar could both 
> penetrate the defences of GH and that Voldemort was happy to be 
> (albeit remotely) watched at work. And if that's *not* how it
works,  then, as I said, on the surviving evidence, what led them to
believe  Harry had survived an AK? I believe there *was* a witness.

Pippin:
Well, of course there were at least three. There was Harry himself, 
whoever abstracted the wand and the robes, and Voldemort.
We know that Harry remembered the green flash, and probably
remembers more than that in his Potterverse-enhanced 
subconscious. Dumbledore needed only to extract Harry's memories
and plop them into the pensieve to see *exactly* what happened,
including things Harry himself didn't see.

Maybe the Ministry directly detected the AK and maybe it didn't,
but  I doubt that Crouch Sr. would be willing to believe that anything
*but* a killing curse could have got rid of Voldemort. He had 
authorized its use, and it wouldn't have looked so good if there
were a way to get rid of LV without it. 

Pippin