I know who did it by Episode 2(spolier black used)...

...dont tell me. But at 30 minutes in (the funeral) I say it HAS to be idiot boy Frankie. No other logical person. Her own brother!! Why, I dont know yet.

I am usually not all that good at predicting. But I have a very strong feeling I am right.

Right or not, it is the JOURNEY that counts in this show. Loving it.

EDIT: HA! I was right. I actually had my doubts a a few times as the series progressed. But I left this comment stay up. I am glad I did.
I dont usually get the murderer right in these types of mysteries.
Turns out Frankie was her son. That I did not see. But I just knew he was the one that shot her. The show did give some clues to that effect