y i think so??
well i got the below theory from an author on ff.net, and i think its very accurate... read on and let me know what u guys think??
"I know who R.A.B. is. He he he. It's not too hard to figure out and it sets up great seventh book possibilities. Do you want to know? Of course you do. It's REGULAS ALPHARD BLACK! That's why Sirius had to die.
Also I know where Slytherin's locket is. It's in #12 Grimmault Place. Re-read OOTP if you don't believe me. Pay particular attention to when they're cleaning the house. This also supports my R.A.B. theory.
For those of you who wondered where I got RAB's middle name from, I have to confess it isn't anywhere in the books as far as I can tell. I am deducing that is what the middle name was because that was the name of Sirius's uncle who gave him money when he left home and JKR tends to give her characters family middle names, for example Ron BILIUS Weasley and Harry JAMES Potter."