DD knew Moody=Barty Crouch before Polyjuice expired

[caesian]

No: HPFGUIDX 122751

Why does Dumbledore request that Professor Snape retrieve Winky from 
the kitchens BEFORE the polyjuice potion had worn off?  I cannot think 
of a good reason for her to be present except that the imposter was 
Barty Crouch Jr.

How much of Barty Jr's story did DD already know?  And why?

If he involved Winky, it seems likely that DD already knew most of the 
saga of Mr. Crouch Sr., Winky and Master Barty.  Perhaps he only 
discovered this recently, or perhaps he has known for many years.  He 
tells Harry earlier that he does not know whether Barty Jr. was 
innocent or guilty.  However, if the alternative involved Dementors, it 
seems reasonable that DD would not have involved himself.

So, it seems as if at the time of the third task Dumbledore already 
knew that an imposter was at Hogwarts, and the true identity of the 
imposter (Barty Crouch Jr.), but apparently not who was being 
impersonated.  (He mentions to Harry that he knew Imposter!Moody was 
not the real Moody only when Imposter!Moody removed Harry after the 
third task.)

It may also be significant that it was Professor Snape who was asked to 
retrieve Winky.  Perhaps Dumbledore knew Barty Jr. was on campus 
because Snape had provided this information covertly - in his function 
as a spy.  Thus Snape was asked to retrieve Winky because someone else 
might have wondered why later.


Caesian, who is curious about who here sleeps with Stephen Fry?  I mean 
the audio books, of course.