I know statistically in these instances, the husband is involved, and yes some things look bad for him (especially the timing of when he leaves and when the killer shows up), but I really don’t think he’s involved. If he were, I believe the police would have made a connection and he would have been arrested by now. I know we don’t know for sure, but as I’ve posted before, I think it’s a man in a woman’s costume. And if it is a man in a woman’s costume (or even a woman in a costume), there has to be a connection to their Star Wars group, a group whose members .. wait for it... dress up in highly detailed Star Wars costumes (duh). Could it be that simple? Maybe it’s not a Star Wars costume, but a different kind of costume to conceal the killer’s identity. Also, if the killer wanted Sergio dead too, they could have just shown up earlier to take them both out. I have a feeling Liz unintentionally set someone off within the Star Wars group, and this person hired someone to kill her. Instead of a note, the killer shows Liz a picture of the person she hurt in some way so they confirm Liz as a target, then kills Liz. It seemed pretty important to the person(s) that killed her that they showed & told Liz something (“This is what you get for ________”) before killing her.