Who was responsible for Sirius' death? ...

[pippin_999]

No: HPFGUIDX 167615

Dana:
> Pg 732 UKed Paperback
> 
> `When, however you did not return from your trip into the Forest with 
> Dolorus Umbridge, Professor Snape grew worried that you still 
> believed Sirius to be a captive of Lord Voldemort's. He alerted 
> certain Order Members at once.'
> 
> End Quote from Canon. 
> 
> If this is truly Snape's account of events then how does he know they 
> went into the Forest? 

Pippin:
He could  have found out from the IS members. They were hit with
a couple of stunners, impedimenta, a disarming charm and a bat
bogey hex, which means that at most only two of them were 
unconscious. There were at least five: Bulstrode, Warrington, 
Malfoy, Crabbe and an unnamed Slytherin sixth year girl. Any of
them could have heard the DA say where they were going, or 
even seen it from the window themselves. 

But they would have no reason to tell Snape about it immediately.
As far as they knew, there really was a weapon, and it wouldn't
be something that Umbridge would want Snape to know about,
since he had been placed on probation. Snape would also have
to be careful that his questions didn't reveal too much -- he
would have to keep up his pretence that he didn't know  or
care what Harry was trying to tell him.

Suppose he finally gathers that Harry and Hermione had
decoyed Umbridge into the forest and the rest of the DA had
gone after them. Considering the state of the IS, Snape
would logically conclude that if anybody  needs rescuing, it is 
probably Umbridge, and he needn't be in a hurry to help
her. 

The IS is  unlikely to have told Snape that Umbridge
threatened to Crucio Harry or that she was the one 
who sent dementors after him. As far as Snape knows, the
worst thing she's done to Harry is keep him from playing
Quidditch -- he may not even know about the Quill. 

Pippin