Contains SPOILERS for the Season 3 premiere of Arrow. (No, not everyone has seen it yet...!)
So this is my analysis of what may or may not have happened at the end of the Season 3 premiere, "The Calm." Without the benefits of re-watching and reviewing the scene, and without any other outside knowledge, such as the Season 2.5 digital comics.
I'm going out on a limb here; you can all laugh at me when I get it wrong ;)
I was thinking of posting some of my predictions for Season 3, but... I have such a hard time analyzing Malcolm Merlyn until after the whole season is over with, anyway, I decided not to look stupid. Alas, no entertainment for you. ;P
All right, back to the subject at hand (SPOILERS below the cut).
So the question is... was it Malcolm who killed Sara?
My answer is, I'm pretty sure he did not. (No, not 100% sure.) Here's the analysis...
1: The attacker calls Sara's name, and his voice sounds as if his throat has been damaged. This indicates it is not Malcolm because:
1A: Unless the digital comics have a story arc where the League of Assassins is hunting Merlyn and they cut his throat... that doesn't match his voice.
1B: If he wanted to disguise his voice, wouldn't he just use his modulator?
1B corollary: Why would he need to? Merlyn and Sara never really met during the show.
2: The attacker uses the name "Sara."
2A: If Sara was in Starling City hunting Malcolm Merlyn for the League, and he came up behind her and called her name, wouldn't he use her assassin name? (Which I don't know how to spell properly, sorry.) This would be how he would know her from the League.
3: Sara turns around and says, "What are you doing here?" And she does not try to defend herself.
3A: If she HAD been there hunting Merlyn, that's totally not what she would have said, and she certainly wouldn't have stood there and let him stick 3 arrows in her.
So, that's my analysis. Now, it COULD actually be Malcolm Merlyn, under the following circumstances:
1: The writers are screwing with us about the voice thing. Like, for example, in "Trust but Verify," when Diggle records a conversation between Moira and Malcolm. Moira's voice comes out clearly enough that Oliver can recognize it, but the other voice is distorted for some reason, and not recognizeable.
2: It could be Merlyn, if he were trying to disguise himself as someone Sara knew, in order to catch her off guard. He could have been imitating this person's voice, and look for all we know. We don't know if this 'someone' was in the League; he may have been all hooded/masked up.
Now #2 is me being my usual, paranoid, convoluted thinking self. This is not how most people (conspiracy theorists aside) tend to think. Then again... I do believe Malcolm is extremely intelligent, and tackles his problems with detailed plans, and contingency plans (and, as you know, "redundancy" failsafes). So I don't think this is beyond him.
And I won't say it is beyond the writers. The Arrow writers constantly (and pleasantly) surprise me with their stories. So I would not put this past them.
But I still think the odds are more in favor of it not being him. We shall see!