Yes, and when we remember there was a fairly sizable life insurance policy in place to pay Sergio if Liz died, I think it can be narrowed down even further, and that would leave only one. But I wouldn't say this is for sure still!
But the life insurance was, I think, $375,000? Not sure if I just pulled that number out of my... er... hat, or if that was actually what it was. And to me, the fact that Sergio never claimed the payout does not mean that the life insurance money wasn't the motive, or A motive, or part of the motive! That is, not if Sergio was NOT involved, and I believe (I think) that he was not. I think he may have known after the fact who did it though. And maybe he was so mad about it (who wouldn't be!) that not claiming the insurance money might have been his way of showing his anger or sort of getting back at the person who did it. Or to express his righteousness, for lack of a better word.
Think about if someone killed Liz, because they thought that it would benefit Sergio financially, and possibly themselves as well thru a sort of trickle-down effect, but they didn't tell Sergio their plan, since that would allow Sergio's hands to stay clean, so to speak. Their plan would make Sergio richer without him having to do something he would himself never do. He could reap the benefits without having to be the bad guy. He could claim the money with a clean conscience, because he had nothing to do with her death. He wasn't the one who killed her, he wasn't part of the plan, he didn't conspire with the killer, he didn't drive the getaway car or participate in any way, he had no advance or post knowledge of the plan. He didn't even see it happen. He wasn't even there!
So whoever this someone is thinks it's all set up so that Sergio will stay squeaky clean, won't be suspected, because he really was left totally in the dark... and he can collect the insurance money with a clean conscience. And maybe Sergio will throw a little money his way every now and then, and now everyone's happy.
But Sergio might have figured it out after the murder, or at least had his suspicions. And he's appalled and outraged that anyone would do this to his Liz, and even worse, do this because they thought it would help Sergio! But for some very tough reasons, he can't do anything about it, because he can't bring Liz back, for the main thing, but also because he can't bring himself to turn the killer in to LE, for those tough reasons I mentioned. He can't really even let the killer know how outraged he is, because then it would look like he (Sergio) knew about the plan, even if only after the fact, plus there's still the fact that the person was really doing it to help him (Sergio). So he's confused. Yes, it was an entirely wrong, misguided way to try to help him out, but it's usually hard to hold it against someone who was trying to do you a favor, even if it ends up hurting you instead... but no! Not in this case! They went too far, even if it was to benefit Sergio, it doesn't matter, they crossed over the line.
But he can't bring himself to turn them in, so all he can do is cut them out of his life, cut off all contact... at least for awhile. Oh, but there's one other thing he can do to SHOW them how wrong they were to do this... he can totally thumb his nose at the insurance money, act like it doesn't exist, never collect it, never even ask about it. That'll probably hurt the one responsible more than anything else he could do! I can imagine how that must just tear them up to know it was all for nothing.
If that is the way it happened. And Sergio did cut off contact for awhile at least. I'm not even sure he ever went back. But I figured he did... time heals all wounds and all that... but if it did happen this way, that is one cold, callous, inhuman plan to come up with and then actually carry out. That would take a seriously sociopathic individual. But that fits too, from the little we have heard about them.