This is really in the tradition of some of the best English murder mysteries. You have multiple suspects each with a plausible or even compelling reason for committing the crime.
Yeah, there are some plausible alternatives to the defendant, but they've been weakly developed. I suppose they've put some effort into the stepdad, but so far he just looks like a sleazebag, not necessarily a murderer. That will obviously play itself out in the finale, but if any of them turn out to be the killer, they're going to have to scramble to make it work in just one more episode.
I have a feeling right now that what will happen is that Naz will be convicted, but there may be some doubt left about his guilt. And that an important aspect of his being led away to spend the rest of his life in prison will be that he's now well prepared for it by his time at Rikers. I don't think that could be emphasized too strongly - he's already resigned himself to spending the rest of his life in prison.
Actually, I'm beginning to hope that the outcome is along those lines, rather than some sort of Perry Mason courtroom resolution of the case. One thing they've hinted at throughout the series is that Naz has been gradually recalling bits and pieces of the night. I'll bet we see some more of these memories revealed, possibly even the murder.