I have some Sirius questions here ... seriously :)

[Doreen Rich]

No: HPFGUIDX 12236

When it was described about Sirius killing the 13 people, 12 muggles 
(there is that number 12 again) and one wizard, Sirius is said to 
have been laughing. Is this just a "repeated rumor"? If not, why 
would he laugh if he were innocent and witnessing Pettigrew actually 
doing the murders?

Why did Sirius slash the picture of the Fat Lady?

Why didn't Sirius make Harry his Secret Keeper so that he could hide 
and Harry would know where he was? Then, Harry could go live with 
him... couldn't he? 

Doreen_Iowa

"It is our choices, Harry, that show what we truly are, far more than 
our abilities." Albus Dumbledore, Harry Potter and the Chamber of 
Secrets